Addition and subtraction answers.pdf - Moree Web

Subtraction mental strategies – compensation strategySometimes we round one number in the problem to make it easierto do in our heads. Then we adjust our answer to compensate:125 – 49 = 76125 – 50 + 175 + 1 = 76I rounded up by 1, whichmeans I subtracted 1 extraso we need to add 1 back.I took off1 extra soI have toadd 1 back.1Round these numbers to the closest ten. Then show how you rounded bysubtracting or adding the difference. The first one has been done for you.a78 = __________ 80– 2b 59 = __________ 60– 1c 62 = __________ 60 + 2d23 = __________ 20 + 3 e 87 = __________ 90– 3f 99 = __________ 100– 1g 103 = __________100 + 3 h 21 = __________ 20 + 1 i 88 = __________ 90– 22Solve these subtraction problems using compensation. Show your working.a 136 – 29 =107b 145 – 38 =107136 – 30 + 1145 – 40 + 2________ 106 +1 = ________ 107 ________ 105 +2 = ________ 107c 156 – 39 =117d 184 – 48 =136156 – ____ 40 +1184 – ____ 50+2__________ 116+1= ________ 117 __________ 134 +2 = ________ 136Continued on page 25.24E 2SERIESTOPICAddition and SubtractionCopyright © 3P Learning