Arithmetic Grade Six

Lesson One Hundred Sixty-six: X Problems Two


Here's another example:
To solve this problem, start by finding all the combinations which add up to the top number and then try multiplying each pair to see what the product is. 

	SUM of 21		MULTIPLYING
	  1 + 20		  1 * 20 = 20
	  2 + 19		  2 * 19 = 38
	  3 + 18		  3 * 18 = 54
	  4 + 17		  4 * 17 = 68
	  5 + 16		  5 * 16 = 80
	  6 + 15		  6 * 15 = 90
	  7 + 14		  7 * 14 = 98
	  8 + 13		  8 * 13 = 104
	  9 + 12		  9 * 12 = 108
	 10 + 11		 10 * 11 = 110
One of these combinations works:

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