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
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