765-254 + 135-245 is the simplest

765-254 + 135-245 is the simplest

＝（765+135）-（254+246-1）
＝900-（254+246）+1
＝900-500+1
＝401

Simple calculation of 38 times 547 minus 347 times 38 minus 150 times 38

(547-347-150)*38=50*38=1900

(-1/126)/(1/9-2/7+2/3-1/14)

(-1/126)/(1/9-2/7+2/3-1/14)
=-1/126*1/(1/9-4/14+6/9-1/14)
=-1/126*1/(7/9-5/14)
=-1/126*1/(98/126-45/126)
=-1/126*1/(53/126)
=-1/126*126/53
=-1/53

Decompose the following numbers into prime factors
39 77 69 28 144 385 255 960 1024

39 =3*13
77=7*11
69=3*23
28=2*2*7
144=2*2*2*2*3*3
385=5*7*11
255=5*51
960=2*2*2*2*2*2*3*5
1024=2*2*2*2*2*2*2*2*2*2