Addition properties and mental strategies
Answers are for parents and teachers.
1
Add in your head with friendly numbers: 175 + 380 + 25 + 120.
175 + 25 = 200 and 380 + 120 = 500, so the sum is 700.
2
Add 57 + 68 by breaking apart and by compensation. Do you get the same answer?
Breaking apart: 57 + 60 + 8 = 125. Compensation: 57 + 70 − 2 = 125. Yes.
3
Add 48,375 + 36,849 in columns.
85,224.
4
Count up to find 1,000 − 586.
586 to 600 is 14 and 600 to 1,000 is 400, so 14 + 400 = 414.
5
Youssef saved 3,750 LE and his sister saved 4,865 LE. How much did they save together? Use the commutative property to check.
3,750 + 4,865 = 8,615 LE. Check: 4,865 + 3,750 = 8,615.