If you need to square a number (two or three digits) that ends in 5, just use this trick. First, you should know that when any number squared that ends in 5 will always have the last two digits of 25. Then all ya need to do is look at the digits before the 5 and multiply it (them) by the next number higher and put that infront of the 25.
Here's two examples:
1) 35 squared is 3 times 4 (one higher than 3) or 12 and put that in front of 25. Looks like this... 1225
2) 65 squared is 6 times 7 (one higher than 6) or 42 and put that in front of 25. Looks like this .... 4225
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