Find the following values without a calculator.
Give your answers in this manner. (Eg 1, 2, 3, 4)

(a) 21 x 9 + 8 x 21 = _____ x 21
(b) 13 x 7 + 7 x 2 + 7 x 5 = _____ x 7 + 2 x 7
(c) 197 x 17 - 9 x 197 = _____ x 197
(d) 15 x 6 + 9 x 6 - 9 x 6 = 19 x 6 - 6 x _____
(a)
21 x 9 + 8 x 21 = _____ x 21
9 x 21 + 8 x 21 = _____ x 21
(9 + 8) x 21 = _____ x 21

17 x 21 =  _____ x 21

(b)
13 x 7 + 7 x 2 + 7 x 5 = _____ x 7 + 2 x 7
(13 + 2 + 5) x 7 = = _____ x 7 + 2 x 7
20 x 7 = _____ x 7 + 2 x 7
20 x 7 - 2 x 7 = _____ x 7
(20 - 2) x 7 = _____ x 7

18 x 7 = _____ x 7

(c)
197 x 17 - 9 x 197 = _____ x 197
(17 - 9) x 197 = _____ x 197

8 x 197 = _____ x 197

(d)
15 x 6 + 9 x 6 - 9 x 6 = 19 x 6 - 6 x _____
(15 + 9 - 9) x 6 = 19 x 6 - _____ x 6
15 x 6 = 19 x 6 - _____ x 6
19 x 6 - 15 x 6 = _____ x 6
(19 - 15) x 6 = _____ x 6

4 x 6 = _____ x 6

Answer(s): 17, 18, 8, 4