Let's solve each day's mental math problems step by step and explain the solutions.
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Monday
1.
65 + 23 =
Add: 65 + 20 = 85, then 85 + 3 =
88
2.
72 - 15 =
Subtract: 72 - 10 = 62, then 62 - 5 =
57
3.
8 × 5 =
8 × 5 =
40
4.
What’s halfway between 50 & 100?
(50 + 100) ÷ 2 = 150 ÷ 2 =
75
5.
Value of the 4 in 482?
The 4 is in the hundreds place →
400
6.
How many sides does a decagon have?
"Deca-" means 10 →
10 sides
7.
Write =, > or <: 82 ___ 82
They are equal →
=
8.
25 + ___ = 52
52 - 25 =
27
9.
1.5 + 1.5 =
1 + 1 = 2, 0.5 + 0.5 = 1 → 2 + 1 =
3.0 or
3
10.
How many 5s make 25?
25 ÷ 5 =
5
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Tuesday
1.
29 + 13 =
29 + 10 = 39, 39 + 3 =
42
2.
95 - 22 =
95 - 20 = 75, 75 - 2 =
73
3.
12 × 5 =
10×5 = 50, 2×5 = 10 → 50 + 10 =
60
4.
What’s halfway between 30 & 50?
(30 + 50) ÷ 2 = 80 ÷ 2 =
40
5.
Value of the 6 in 162?
The 6 is in the tens place →
60
6.
How many sides does a hexagon have?
"Hexa-" means 6 →
6 sides
7.
Write =, > or <: 44 ___ 54
44 is less than 54 →
<
8.
93 + ___ = 113
113 - 93 =
20
9.
1.3 + 0.3 =
1 + 0.3 + 0.3 = 1 + 0.6 =
1.6
10.
How many 2s make 18?
18 ÷ 2 =
9
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Wednesday
1.
84 + 26 =
84 + 20 = 104, 104 + 6 =
110
2.
71 - 21 =
71 - 20 = 51, 51 - 1 =
50
3.
8 × 4 =
8 × 4 =
32
4.
What’s halfway between 16 & 20?
(16 + 20) ÷ 2 = 36 ÷ 2 =
18
5.
Value of the 9 in 392?
The 9 is in the tens place →
90
6.
How many sides does a nonagon have?
"Non-" means 9 →
9 sides
7.
Write =, > or <: 75 ___ 57
75 is greater than 57 →
>
8.
150 + ___ = 325
325 - 150 =
175
9.
0.2 + 0.6 =
0.2 + 0.6 =
0.8
10.
How many 3s make 15?
15 ÷ 3 =
5
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Thursday
1.
18 + 18 =
18 + 18 =
36
2.
96 - 43 =
96 - 40 = 56, 56 - 3 =
53
3.
7 × 4 =
7 × 4 =
28
4.
What’s halfway between 18 & 22?
(18 + 22) ÷ 2 = 40 ÷ 2 =
20
5.
Value of the 6 in 6381?
The 6 is in the thousands place →
6000
6.
How many sides does a circle have?
A circle has
no sides (it's curved) →
0
7.
Write =, > or <: 18 ___ 19
18 is less than 19 →
<
8.
51 + ___ = 77
77 - 51 =
26
9.
4.5 + 1.5 =
4 + 1 = 5, 0.5 + 0.5 = 1 → 5 + 1 =
6.0 or
6
10.
How many 10s make 100?
100 ÷ 10 =
10
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✔ Final Answers:
####
Monday
1. 88
2. 57
3. 40
4. 75
5. 400
6. 10
7. =
8. 27
9. 3
10. 5
####
Tuesday
1. 42
2. 73
3. 60
4. 40
5. 60
6. 6
7. <
8. 20
9. 1.6
10. 9
####
Wednesday
1. 110
2. 50
3. 32
4. 18
5. 90
6. 9
7. >
8. 175
9. 0.8
10. 5
####
Thursday
1. 36
2. 53
3. 28
4. 20
5. 6000
6. 0
7. <
8. 26
9. 6
10. 10
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These are all mental math exercises designed to build fluency in basic arithmetic, number sense, and geometry concepts appropriate for Grade 3 students. Let me know if you'd like these formatted as a printable worksheet!
Parent Tip: Review the logic above to help your child master the concept of worksheet for 3rd graders math.
