Page 8 - Math,prim 2 flip book
P. 8
Delta Modern Language Schools Prim 2
Primary stage
Math Department
term 2024-2025
Chapter 4
➢ Commutative property in addition
❖ You can add in any order and the sum is the same.
EX 5+2 = 7 2+5 = 7
➢ Mental applications on adding and subtraction
Use count on to add Use count back to subtract
what is 5 + 24 ? what is 43 - 4 ?
✓ Start at 24. ✓ Start at 43.
✓ Then count on ✓ Then count back 4
✓ 42,41,40,39
5 more ✓ The difference is 39
✓ 25 ,26,27 ,28 ,29
✓ The sum is 29.
➢ How to decompose a 2-digit number ?
❖ Decompose a 2-digit number means writing it as sum of tens and
ones.
56 50 + 6
✓ The digit 5 is in the tens place. Its means 5 has a value of 50.
✓ The digit 6 is in the ones place. Its means 6 has a value of 6
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