Grade 4 Mental Math Worksheets | Free Worksheets | Printables - Free Printable

The task involves solving a series of addition problems for each day of the week (Monday, Tuesday, Wednesday, and Thursday). Below is the solution for each problem, along with an explanation of how to approach mental math effectively.

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Monday

1. \( 76 + 92 = 168 \)
- Add the tens: \( 70 + 90 = 160 \)
- Add the ones: \( 6 + 2 = 8 \)
- Combine: \( 160 + 8 = 168 \)

2. \( 84 + 84 = 168 \)
- Double 84: \( 84 \times 2 = 168 \)

3. \( 75 + 75 = 150 \)
- Double 75: \( 75 \times 2 = 150 \)

4. \( 69 + 75 = 144 \)
- Add the tens: \( 60 + 70 = 130 \)
- Add the ones: \( 9 + 5 = 14 \)
- Combine: \( 130 + 14 = 144 \)

5. \( 48 + 89 = 137 \)
- Add the tens: \( 40 + 80 = 120 \)
- Add the ones: \( 8 + 9 = 17 \)
- Combine: \( 120 + 17 = 137 \)

6. \( 120 + 490 = 610 \)
- Add the hundreds: \( 100 + 400 = 500 \)
- Add the tens: \( 20 + 90 = 110 \)
- Combine: \( 500 + 110 = 610 \)

7. \( 90 + 190 = 280 \)
- Add the hundreds: \( 0 + 100 = 100 \)
- Add the tens: \( 90 + 90 = 180 \)
- Combine: \( 100 + 180 = 280 \)

8. \( 150 + 480 = 630 \)
- Add the hundreds: \( 100 + 400 = 500 \)
- Add the tens: \( 50 + 80 = 130 \)
- Combine: \( 500 + 130 = 630 \)

9. \( 220 + 910 = 1130 \)
- Add the hundreds: \( 200 + 900 = 1100 \)
- Add the tens: \( 20 + 10 = 30 \)
- Combine: \( 1100 + 30 = 1130 \)

10. \( 670 + 410 = 1080 \)
- Add the hundreds: \( 600 + 400 = 1000 \)
- Add the tens: \( 70 + 10 = 80 \)
- Combine: \( 1000 + 80 = 1080 \)

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Tuesday

1. \( 95 + 66 = 161 \)
- Add the tens: \( 90 + 60 = 150 \)
- Add the ones: \( 5 + 6 = 11 \)
- Combine: \( 150 + 11 = 161 \)

2. \( 142 + 121 = 263 \)
- Add the hundreds: \( 100 + 100 = 200 \)
- Add the tens: \( 40 + 20 = 60 \)
- Add the ones: \( 2 + 1 = 3 \)
- Combine: \( 200 + 60 + 3 = 263 \)

3. \( 67 + 88 = 155 \)
- Add the tens: \( 60 + 80 = 140 \)
- Add the ones: \( 7 + 8 = 15 \)
- Combine: \( 140 + 15 = 155 \)

4. \( 49 + 49 = 98 \)
- Double 49: \( 49 \times 2 = 98 \)

5. \( 36 + 82 = 118 \)
- Add the tens: \( 30 + 80 = 110 \)
- Add the ones: \( 6 + 2 = 8 \)
- Combine: \( 110 + 8 = 118 \)

6. \( 510 + 750 = 1260 \)
- Add the hundreds: \( 500 + 700 = 1200 \)
- Add the tens: \( 10 + 50 = 60 \)
- Combine: \( 1200 + 60 = 1260 \)

7. \( 970 + 140 = 1110 \)
- Add the hundreds: \( 900 + 100 = 1000 \)
- Add the tens: \( 70 + 40 = 110 \)
- Combine: \( 1000 + 110 = 1110 \)

8. \( 760 + 240 = 1000 \)
- Add the hundreds: \( 700 + 200 = 900 \)
- Add the tens: \( 60 + 40 = 100 \)
- Combine: \( 900 + 100 = 1000 \)

9. \( 580 + 750 = 1330 \)
- Add the hundreds: \( 500 + 700 = 1200 \)
- Add the tens: \( 80 + 50 = 130 \)
- Combine: \( 1200 + 130 = 1330 \)

10. \( 120 + 860 = 980 \)
- Add the hundreds: \( 100 + 800 = 900 \)
- Add the tens: \( 20 + 60 = 80 \)
- Combine: \( 900 + 80 = 980 \)

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Wednesday

1. \( 69 + 88 = 157 \)
- Add the tens: \( 60 + 80 = 140 \)
- Add the ones: \( 9 + 8 = 17 \)
- Combine: \( 140 + 17 = 157 \)

2. \( 29 + 58 = 87 \)
- Add the tens: \( 20 + 50 = 70 \)
- Add the ones: \( 9 + 8 = 17 \)
- Combine: \( 70 + 17 = 87 \)

3. \( 144 + 99 = 243 \)
- Add the hundreds: \( 100 + 0 = 100 \)
- Add the tens: \( 40 + 90 = 130 \)
- Add the ones: \( 4 + 9 = 13 \)
- Combine: \( 100 + 130 + 13 = 243 \)

4. \( 261 + 182 = 443 \)
- Add the hundreds: \( 200 + 100 = 300 \)
- Add the tens: \( 60 + 80 = 140 \)
- Add the ones: \( 1 + 2 = 3 \)
- Combine: \( 300 + 140 + 3 = 443 \)

5. \( 67 + 77 = 144 \)
- Add the tens: \( 60 + 70 = 130 \)
- Add the ones: \( 7 + 7 = 14 \)
- Combine: \( 130 + 14 = 144 \)

6. \( 140 + 810 = 950 \)
- Add the hundreds: \( 100 + 800 = 900 \)
- Add the tens: \( 40 + 10 = 50 \)
- Combine: \( 900 + 50 = 950 \)

7. \( 350 + 170 = 520 \)
- Add the hundreds: \( 300 + 100 = 400 \)
- Add the tens: \( 50 + 70 = 120 \)
- Combine: \( 400 + 120 = 520 \)

8. \( 470 + 510 = 980 \)
- Add the hundreds: \( 400 + 500 = 900 \)
- Add the tens: \( 70 + 10 = 80 \)
- Combine: \( 900 + 80 = 980 \)

9. \( 370 + 470 = 840 \)
- Add the hundreds: \( 300 + 400 = 700 \)
- Add the tens: \( 70 + 70 = 140 \)
- Combine: \( 700 + 140 = 840 \)

10. \( 840 + 210 = 1050 \)
- Add the hundreds: \( 800 + 200 = 1000 \)
- Add the tens: \( 40 + 10 = 50 \)
- Combine: \( 1000 + 50 = 1050 \)

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Thursday

1. \( 47 + 62 = 109 \)
- Add the tens: \( 40 + 60 = 100 \)
- Add the ones: \( 7 + 2 = 9 \)
- Combine: \( 100 + 9 = 109 \)

2. \( 118 + 94 = 212 \)
- Add the tens: \( 100 + 90 = 190 \)
- Add the ones: \( 18 + 4 = 22 \)
- Combine: \( 190 + 22 = 212 \)

3. \( 321 + 215 = 536 \)
- Add the hundreds: \( 300 + 200 = 500 \)
- Add the tens: \( 20 + 10 = 30 \)
- Add the ones: \( 1 + 5 = 6 \)
- Combine: \( 500 + 30 + 6 = 536 \)

4. \( 88 + 28 = 116 \)
- Add the tens: \( 80 + 20 = 100 \)
- Add the ones: \( 8 + 8 = 16 \)
- Combine: \( 100 + 16 = 116 \)

5. \( 62 + 112 = 174 \)
- Add the tens: \( 60 + 110 = 170 \)
- Add the ones: \( 2 + 2 = 4 \)
- Combine: \( 170 + 4 = 174 \)

6. \( 450 + 350 = 800 \)
- Add the hundreds: \( 400 + 300 = 700 \)
- Add the tens: \( 50 + 50 = 100 \)
- Combine: \( 700 + 100 = 800 \)

7. \( 860 + 320 = 1180 \)
- Add the hundreds: \( 800 + 300 = 1100 \)
- Add the tens: \( 60 + 20 = 80 \)
- Combine: \( 1100 + 80 = 1180 \)

8. \( 980 + 160 = 1140 \)
- Add the hundreds: \( 900 + 100 = 1000 \)
- Add the tens: \( 80 + 60 = 140 \)
- Combine: \( 1000 + 140 = 1140 \)

9. \( 9530 + 510 = 10040 \)
- Add the thousands: \( 9000 + 0 = 9000 \)
- Add the hundreds: \( 500 + 500 = 1000 \)
- Add the tens: \( 30 + 10 = 40 \)
- Combine: \( 9000 + 1000 + 40 = 10040 \)

10. \( 860 + 310 = 1170 \)
- Add the hundreds: \( 800 + 300 = 1100 \)
- Add the tens: \( 60 + 10 = 70 \)
- Combine: \( 1100 + 70 = 1170 \)

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Final Answers

- Monday: \( 168, 168, 150, 144, 137, 610, 280, 630, 1130, 1080 \)
- Tuesday: \( 161, 263, 155, 98, 118, 1260, 1110, 1000, 1330, 980 \)
- Wednesday: \( 157, 87, 243, 443, 144, 950, 520, 980, 840, 1050 \)
- Thursday: \( 109, 212, 536, 116, 174, 800, 1180, 1140, 10040, 1170 \)

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Boxed Final Answer

\[
\boxed{
\begin{aligned}
&\text{Monday: } 168, 168, 150, 144, 137, 610, 280, 630, 1130, 1080 \\
&\text{Tuesday: } 161, 263, 155, 98, 118, 1260, 1110, 1000, 1330, 980 \\
&\text{Wednesday: } 157, 87, 243, 443, 144, 950, 520, 980, 840, 1050 \\
&\text{Thursday: } 109, 212, 536, 116, 174, 800, 1180, 1140, 10040, 1170
\end{aligned}
}
\]