Approximating

Find an approximate answer for each summ then choose a number from the list which could be the correct answer

a) 487 + 246 + 175

b) 813 - 469 + 257

c) 829 + 752 - 483

d) 883 - 324 - 178

e) 791 - 254 + 509

f) 267 + 394 + 443

Four pupils each did 7291 + 4825 + 3428 on thier calculators. Use rounding to get an approximate of the answer and tell who got the correct answer?
Who got the correct answer to this calculation: 8724 - 3291 + 6597