When multiplying 2 digit numbers that are the same number. There are 2 ways to achieve the right answer here. Just do it with the one that you are the most comfortable with.
The first thing you should know is that any number that ends in “5”, when you multiply it by itself, the answer always ends with “25”.
Let’s say you have the problem 25x25. For this one, the answer is 625. I got that mostly by just straight multiplying. As I said earlier, it ends with “25”. To get the “6” I just did 2x2+2. If the problem is 45x45 then you do 4x4+4, then add the “25. So 45x45 is 2025. If it’s 85x85 then it’s 8x8+8 (72), add the “25” and you get 7225.
Try a few on your own before we get into the second method of achieving this. You might possibly think that the second method is even easier than the first one.
For the second method, all you need to do is manipulate one of the first numbers. In our 25x25 example, you would change one of the 2’s to the next higher number, a 3. Then you just multiply straight down. With 25x25 it would be 35x25 and multiplying straight down is 3x2=6 and 5x5 is 25, so 25x25=625. If you have 65x65, then you convert it to 75x65, the answer, 4225. 95x95 = 9025.
Simple, right? Any questions? Feel free to ask them here and I'll do my best to answer them all.
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