Use compatible numbers to estimate.
9. 83 + 34
10. 329 + 64
11. 212 + 347
12. 537 + 244
83 + 34 = 83 + 37 - 3 = 120 - 3 = 117
329 + 64 = 330 - 1 + 60 + 4 =
390 + 3 = 393
212 + 347 = 213 - 1 + 347 =
600 - 1 = 559
537 + 244 = 537 + 243 + 1 =
780 + 1 = 781