2356
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
578 + 945 = 1523
945 - 25 = 920
387 + 1582 = 1969
387 + 285 = 672
1860
945
2048
1,412
387
1028.
9.0 × 1024