Medium
Find the missing number in the grid: Row1: 1, 6, 7 | Row2: 2, 5, 9 | Row3: 3, 4, ?
Explanation
Explanation
The third column equals (1st number squared) plus the 2nd number. Row 1: 1 squared + 6 = 7, correct. Row 2: 2 squared + 5 = 9, correct. Row 3: 3 squared + 4 = 9+4 = 13, so the missing number is 13.
PRO TIP
Re-check your working by substituting the answer back into the original question.