To get 70 pieces, you need to cut enough rows and columns so the product (multiply them together) of those two is 70. There are several ways to make 70:
70 * 1 (duh)
35 * 2
14 * 5
10 * 7
Of those, I'd guess 10 x 7 is your best bet, with the long dimension cut into 10 and the short dimension cut into 7.
Both 71 and 73 are prime numbers, so it'd be difficult to cut that many pieces. 74 is hard too as its "almost" prime. There are a lot of things which multiple to 72, so that's a good one to use:
72 * 1
32 * 2
24 * 3
18 * 4
12 * 6
9 * 8
I'm guessing 9x8 would work OK, especially since 8 is easy to cut.
EDIT: Just to clarify, this is the number of pieces to cut in each direction, not the size of each piece. So 9x8 pieces would each be 24 in./9 pieces = 2⅔ in. by 16 in./8 pieces = 2 in. So the pieces would be 2⅔×2 in. The attached picture should explain
|