To estimate a number you round it up to easier number so 387 would be 400. 945 would be 950 and 1024 would be 1030.
so 400 and 950 would be 1350 plus 1030 equals 2380
you could even round it up easier so 400 plus 900 and 1000 equals 2300
2356
578 + 945 = 1523
945 - 25 = 920
1860
945
1,412
39% of 945 = 39% * 945 = 0.39 * 945 = 368.55
1 and 945
45
945
945-666 = 279
LCM(3, 27, 35) = 945