42x36÷24x17
=1512÷24×17
=63×17
=1071
36x63-63x34
=﹙36－34﹚×63
=2×63
=126
25x{40+8}x125
=﹙25×40＋25×8﹚×125
=﹙1000＋200）×125
=1200×125
=1500
637-252÷21+412
=637－12＋412
=637＋400
=1037
25x4÷25x4
=100÷25×4
=4×4
=16