Addition and Subtraction Strategies A Little Bit More/A Little Bit Less Homework sheet
I am learning to solve multiplication problems by taking some off or putting some on (Compensation)
Exercise 1 What to do
Use the information given to you to derive the answer to a similar problem.
1) If 3 × 40 = 120 what is 3 × 41 ?
123 because 3x40 is 120+3=123.
2) If 8 × 50 = 400 what is 8 × 51 ?
408 because 8x50 is 400+8=408.
3) If 4 × 70 = 280 what is 4 × 72 ?
284 because 4x70 is 280+4=284
Exercise 2 What to do
Use the information given to you to derive the answer to a similar problem.
1) If 7 × 30 = 210 what is 7 × 29 ?
203 because 7x30 is 210-7=203.
2) If 8 × 80 = 640 what is 8 × 79 ?
632 because 8x80 is 640-8=632.
3) If 6 × 20 = 120 what is 6 × 19 ?
114 because 6x20 is 120-6=114.
Exercise 3 What to do
Use the information given to you to derive the answer to a similar problem.
1) If 9 × 40 = 360 what is 9 × 42 ?
378 because 9x40 is 360+18=378
2) If 7 × 30 = 210 what is 7 × 33 ?
231 because 7x30 is 210+21=231
3) If 5 × 40 = 200 what is 5 × 42 ?
210 because 5x40 is 200+10=210.
Exercise 4 What to do
Use the information given to you to derive the answer to a similar problem.
1) If 6 × 40 = 240 what is 6 × 38 ?
228 because 6x40 is 240-12=228
2) If 7 × 60 = 420 what is 7 × 57 ?
399 because 7x60 is 420-21=399
3) If 5 × 30 = 150 what is 5 × 28 ?
140 because 5x30 is 150-10=140
Exercise 5 What to do
Use the information given to you to derive the answer to a similar problem.
1) If 4 × 600 = 2400 what is 4 × 601 ?
2404 because 4x600 is 2400+4=2404
2) If 7 × 800 = 5600 what is 7 × 801 ?
5607 because 7x800 is 5600+7=5607
3) If 3 × 400 = 1200 what is 3 × 402 ?
1206 because 3x400 is 1200+6=1206
Exercise 6 What to do
Use the information given to you to derive the answer to a similar problem.
1) If 9 × 200 = 1800 what is 9 × 199 ?
1791 because 9x200 is 1800-9=1791
2) If 5 × 300 = 1500 what is 5 × 299 ?
1495 because 5x300 is 1500-5=1495
3) If 3 × 400 = 1200 what is 3 × 398 ?
1194 because 3x400 is 1200-6=1194
Exercise 7 What to do
Use the information given to you to derive the answer to a similar problem.
1) If 2 × 25 = 50 what is 2 × 23 ?
46 because 2x25 is 50-4=46
2) If 4 × 25 = 100 what is 4 × 26 ?
104 because 4x25 is 100+4=104.
3) If 3 × 15 = 45 what is 3 × 16 ?
48 because 3x15 is 45+3=48
Exercise 8 What to do
Use the strategy add a little/subtract a little to solve these problems.
Julie wanted to find 3 × 28.
She knows that 28 is near 30, so she used 3 × 30 = 90 and subtracted 3 × 2 = 6 to get the answer.
Julie recorded this in her maths book
3 × 28 = 90 – 6 = 84
Using Julie’s method find the answer to the following problems. Record your working like Julie did.
1) 5 × 19
100 – 5 = 95
5x20=100-5=95
(2) 6 × 41
240 + 6 = 246
6x40=240+6=246
(3) 3 × 59
180 – 3 = 177
3x60=180-3=177
4) 4 × 52
200 + 8 = 208
4x50=200+8=208
(5) 3 × 73
210 + 9 = 219
3x70=210+9=219
(6) 8 × 37
320 – 24 = 296
8x40=320-24=296
7) 3 × 102
300 + 6 = 306
3x100=300+6=306
(8) 6 × 301
1000+6=1006
6x300=1800+6=1006
(9) 8 × 598
4800-16=4784
8x600=4800-16=4784