You should use your calculator for such simple sums. It is far quicker and involves fewer key depressions than posting the question on WA.
21 = 1 x 21, 3 x 7, 7 x 3, 21 x 1.
21 = 1 x 21, 3 x 7, 7 x 3, 21 x 1
1 x 21, 3 x 7, 7 x 3, 21 x 1
1 x 21, 3 x 7, 7 x 3, 21 x 1
10
x-3-7x=21 -6x=21+3 6x=-24 x=-4
Four ways. 4 1 x 21 = 21 21 x 1 = 21 3 x 7 = 21 7 x 3 = 21
3 times what = 63
1 x 21, 3 x 7, 7 x 3, 21 x 1
3 * 21 = 3*(20 + 1) = 3*20 + 3*1 = 60 + 3 = 63.
21 3,7 3 x 7 = 21
3 x 7 x 7 x 11 x 13