4-Digit Addition Missing Numbers Challenge 2 worksheet for practicing arithmetic skills.

Let’s solve each problem one by one. We’ll fill in the missing digits so that the addition is correct.

We’ll go step by step for each problem, checking column by column (from right to left — ones, tens, hundreds, thousands) and making sure carries are handled properly.

---

Problem 1:
```
4836
+ 1_2_
------
_3_4
```

Start from the rightmost column (ones place):

- Ones: 6 + ? = ends in 4 → must be 8 (because 6+8=14, write 4, carry 1)
→ So second number’s ones digit is 8

Now tens place:
- Tens: 3 + 2 + carry(1) = 6 → but result shows _ (tens digit of sum). Wait — let’s look again.

Actually, the sum is written as `_3_4`, meaning:

Thousands | Hundreds | Tens | Ones
? | 3 | ? | 4

So:

Ones: 6 + ? = 4 or 14 → only possible if ? = 8 (6+8=14 → write 4, carry 1)

Tens: 3 + 2 + carry(1) = 6 → so tens digit of sum is 6 → so sum is `_364`

Hundreds: 8 + ? = 3 or 13 → since we have a carry? Let’s see:

Wait — actually, the first number is 4836, second is 1_2_, sum is _3_4.

Let me rewrite with blanks:

```
4 8 3 6
+ 1 A 2 B
----------
C 3 D 4
```

From ones: 6 + B = 4 or 14 → B = 8 (carry 1)

Tens: 3 + 2 + 1(carry) = 6 → so D = 6

Hundreds: 8 + A = 3 or 13 → 8+A=13 → A=5 (carry 1)

Thousands: 4 + 1 + 1(carry) = 6 → so C = 6

Check: 4836 + 1528 = 6364 → yes!

✔ Answer: 1528 and 6364 → missing digits: 5,8,6,6 → but question asks to work out missing numbers — probably fill in the blanks.

In original:

First addend: 1_2_ → becomes 1528
Sum: _3_4 → becomes 6364

So missing digits: 5,8,6,6 — but we’ll list full corrected equations later.

Let’s do all problems similarly.

---

Problem 2:
```
_90_
+ 25_6
------
4_81
```

Let’s denote:

A90B
+25C6
=4D81

Ones: B + 6 = 1 or 11 → B=5 (since 5+6=11 → write 1, carry 1)

Tens: 0 + C + 1 = 8 → C=7

Hundreds: 9 + 5 = 14 → write 4, carry 1 → so D=4? But sum has 4_81 → hundreds digit is D, which should be 4? Wait:

Wait — sum is 4_D_81? No — it's 4 _ 8 1 → so thousands=4, hundreds=?, tens=8, ones=1.

After tens: we have 0+C+1=8 → C=7

Hundreds: 9 + 5 = 14 → write 4, carry 1 → so hundreds digit of sum is 4 → so D=4

Thousands: A + 2 + 1(carry) = 4 → A=1

Check: 1905 + 2576 = 4481 → yes!

✔ Missing: A=1, B=5, C=7, D=4

---

Problem 3:
```
7_34
+ _39_
------
99_1
```

Let:

7A34
+B39C
=99D1

Ones: 4 + C = 1 or 11 → C=7 (4+7=11 → write 1, carry 1)

Tens: 3 + 9 + 1 = 13 → write 3, carry 1 → so D=3

Hundreds: A + 3 + 1 = 9 → A=5

Thousands: 7 + B = 9 → B=2

Check: 7534 + 2397 = 9931 → yes!

✔ A=5, B=2, C=7, D=3

---

Problem 4:
```
52_5
+ __36
------
_271_
```

Let:

52A5
+BC36
=D271E

Ones: 5+6=11 → E=1, carry 1

Tens: A + 3 + 1 = 1 → wait, sum tens digit is 1? But 52A5 + BC36 = D271E → tens digit is 1.

So: A + 3 + 1(carry) = 1 or 11 → must be 11 → A=7 (7+3+1=11 → write 1, carry 1)

Hundreds: 2 + C + 1 = 7 → C=4

Thousands: 5 + B = 2 or 12 → 5+B=12 → B=7 (carry 1)

Ten-thousands: carry 1 → D=1

Check: 5275 + 7436 = 12711 → yes!

✔ A=7, B=7, C=4, D=1, E=1

---

Problem 5:
```
362_
+ 2_63
------
_1_2
```

Let:

362A
+2B63
=C1D2

Ones: A+3=2 or 12 → A=9 (9+3=12 → write 2, carry 1)

Tens: 2+6+1=9 → D=9

Hundreds: 6+B=1 or 11 → 6+B=11 → B=5 (carry 1)

Thousands: 3+2+1=6 → C=6

Check: 3629 + 2563 = 6192 → yes!

✔ A=9, B=5, C=6, D=9

---

Problem 6:
```
82_4
+ _68_
------
_1_51
```

Let:

82A4
+B68C
=D1E51 → wait, sum is 5-digit? Original says "_1_51" — likely 5 digits.

Looking back: “_1_51” — probably 5 digits: ten-thousands, thousands, hundreds, tens, ones.

So:

82A4
+B68C
=F1G51

Ones: 4+C=1 or 11 → C=7 (4+7=11 → write 1, carry 1)

Tens: A+8+1=5 or 15 → A+9=15 → A=6 (write 5, carry 1)

Hundreds: 2+6+1=9 → G=9

Thousands: 8+B=1 or 11 → 8+B=11 → B=3 (carry 1)

Ten-thousands: carry 1 → F=1

Check: 8264 + 3687 = 11951 → yes!

✔ A=6, B=3, C=7, F=1, G=9

---

Problem 7:
```
45_8
+ _94_
------
7_84
```

Let:

45A8
+B94C
=7D84

Ones: 8+C=4 or 14 → C=6 (8+6=14 → write 4, carry 1)

Tens: A+4+1=8 → A=3

Hundreds: 5+9=14 → write 4, carry 1 → D=4

Thousands: 4+B+1=7 → B=2

Check: 4538 + 2946 = 7484 → yes!

✔ A=3, B=2, C=6, D=4

---

Problem 8:
```
_08_
+ 5_72
------
_25_8
```

Let:

A08B
+5C72
=D25E8 → wait, sum is 5 digits? "_25_8" — likely 5 digits.

Original: "_25_8" — positions: ten-thousands, thousands, hundreds, tens, ones → so 5 digits.

So:

A08B
+5C72
=F25G8

Ones: B+2=8 → B=6

Tens: 8+7=15 → write 5, carry 1 → G=5

Hundreds: 0+C+1=2 → C=1

Thousands: A+5=2 or 12 → A+5=12 → A=7 (carry 1)

Ten-thousands: carry 1 → F=1

Check: 7086 + 5172 = 12258 → yes!

✔ A=7, B=6, C=1, F=1, G=5

---

Problem 9:
```
_8_1
+ 4_8_
------
_1316
```

Let:

A8B1
+4C8D
=E1316

Ones: 1+D=6 → D=5

Tens: B+8=1 or 11 → B+8=11 → B=3 (carry 1)

Hundreds: 8+C+1=3 or 13 → 8+C+1=13 → C=4 (carry 1)

Thousands: A+4+1=1 or 11 → A+5=11 → A=6 (carry 1)

Ten-thousands: carry 1 → E=1

Check: 6831 + 4485 = 11316 → yes!

✔ A=6, B=3, C=4, D=5, E=1

---

Problem 10:
This one has THREE numbers!

```
5_72
+ 20_5
+ _503
------
_122_
```

Let:

5A72
+20B5
+C503
=D122E

Add column by column, right to left.

Ones: 2+5+3=10 → E=0, carry 1

Tens: 7+B+0+1=2 or 12 → 7+B+1=12 → B=4 (carry 1)

Hundreds: A+0+5+1=2 or 12 → A+6=12 → A=6 (carry 1)

Thousands: 5+2+C+1=1 or 11 → 8+C=11 → C=3 (carry 1)

Ten-thousands: carry 1 → D=1

Check: 5672 + 2045 + 3503 = 11220 → yes!

✔ A=6, B=4, C=3, D=1, E=0

---

Problem 11:
Three numbers again:

```
_14_
+ 16_5
+ 2_17
------
_1685
```

Let:

A14B
+16C5
+2D17
=E1685

Ones: B+5+7=5 or 15 → B+12=15 → B=3 (carry 1)

Tens: 4+C+1+1=8 → 4+C+2=8 → C=2

Hundreds: 1+6+D=6 or 16 → 7+D=16 → D=9 (carry 1)

Thousands: A+1+2+1=1 or 11 → A+4=11 → A=7 (carry 1)

Ten-thousands: carry 1 → E=1

Check: 7143 + 1625 + 2917 = 11685 → yes!

✔ A=7, B=3, C=2, D=9, E=1

---

Problem 12:
Three numbers:

```
_618
+ 22_4
+ 5_49
------
_224_
```

Let:

A618
+22B4
+5C49
=D224E

Ones: 8+4+9=21 → E=1, carry 2

Tens: 1+B+4+2=4 or 14 → 1+B+6=14 → B=7 (carry 1)

Hundreds: 6+2+C+1=2 or 12 → 9+C=12 → C=3 (carry 1)

Thousands: A+2+5+1=2 or 12 → A+8=12 → A=4 (carry 1)

Ten-thousands: carry 1 → D=1

Check: 4618 + 2274 + 5349 = 12241 → yes!

✔ A=4, B=7, C=3, D=1, E=1

---

Problem 13:
Three numbers:

```
72_6
+ 4_77
+ 260_
------
__066
```

Let:

72A6
+4B77
+260C
=DE066

Ones: 6+7+C=6 or 16 → 13+C=16 → C=3 (carry 1)

Tens: A+7+0+1=6 or 16 → A+8=16 → A=8 (carry 1)

Hundreds: 2+B+6+1=0 or 10 → 9+B=10 → B=1 (carry 1)

Thousands: 7+4+2+1=14 → write 4, carry 1 → so D=1, E=4? Sum is DE066 → so thousands digit is E, ten-thousands is D.

After thousands: 7+4+2+1=14 → write 4, carry 1 → so E=4, then ten-thousands: carry 1 → D=1

Check: 7286 + 4177 + 2603 = 14066 → yes!

✔ A=8, B=1, C=3, D=1, E=4

---

Problem 14:
Three numbers:

```
61_9
+ _713
+ 355_
------
_2_26
```

Let:

61A9
+B713
+355C
=D2E26

Ones: 9+3+C=6 or 16 → 12+C=16 → C=4 (carry 1)

Tens: A+1+5+1=2 or 12 → A+7=12 → A=5 (carry 1)

Hundreds: 1+7+5+1=14 → write 4, carry 1 → E=4

Thousands: 6+B+3+1=2 or 12 → 10+B=12 → B=2 (carry 1)

Ten-thousands: carry 1 → D=1

Check: 6159 + 2713 + 3554 = 12426 → yes!

✔ A=5, B=2, C=4, D=1, E=4

---

Problem 15:
Three numbers:

```
9_48
+ 48_6
+ _48_
------
_1647
```

Let:

9A48
+48B6
+C48D
=E1647

Ones: 8+6+D=7 or 17 → 14+D=17 → D=3 (carry 1)

Tens: 4+B+8+1=4 or 14 → 13+B=14 → B=1 (carry 1)

Hundreds: A+8+4+1=6 or 16 → A+13=16 → A=3 (carry 1)

Thousands: 9+4+C+1=1 or 11 → 14+C=11? Wait — 9+4+C+1 = 14+C → must equal 11 or 21? Since sum is E1647 → thousands digit is 1, so 14+C must end with 1 → 14+C=21 → C=7 (carry 2)

Ten-thousands: carry 2 → E=2

Check: 9348 + 4816 + 7483 = 21647 → yes!

✔ A=3, B=1, C=7, D=3, E=2

---

Now, compiling all answers as filled-in equations:

1) 4836 + 1528 = 6364
2) 1905 + 2576 = 4481
3) 7534 + 2397 = 9931
4) 5275 + 7436 = 12711
5) 3629 + 2563 = 6192
6) 8264 + 3687 = 11951
7) 4538 + 2946 = 7484
8) 7086 + 5172 = 12258
9) 6831 + 4485 = 11316
10) 5672 + 2045 + 3503 = 11220
11) 7143 + 1625 + 2917 = 11685
12) 4618 + 2274 + 5349 = 12241
13) 7286 + 4177 + 2603 = 14066
14) 6159 + 2713 + 3554 = 12426
15) 9348 + 4816 + 7483 = 21647

Final Answer:
1) 1528, 6364
2) 1905, 2576, 4481
3) 7534, 2397, 9931
4) 5275, 7436, 12711
5) 3629, 2563, 6192
6) 8264, 3687, 11951
7) 4538, 2946, 7484
8) 7086, 5172, 12258
9) 6831, 4485, 11316
10) 5672, 2045, 3503, 11220
11) 7143, 1625, 2917, 11685
12) 4618, 2274, 5349, 12241
13) 7286, 4177, 2603, 14066
14) 6159, 2713, 3554, 12426
15) 9348, 4816, 7483, 21647