Let's solve this simple addition problem: 90 plus 9. We start with 90 and add 9 to get 99.
We can visualize this addition using blocks. Here we have 90 blue blocks arranged in a grid, and 9 red blocks. When we combine them together, we get a total of 99 blocks.
Let's solve this step by step. We start with 90 plus 9. We can think of 9 as 10 minus 1. So 90 plus 9 equals 90 plus 10 minus 1, which is 100 minus 1, giving us 99.
Another way to solve this is using a number line. We start at 90 and count forward 9 positions. This brings us to 99, confirming our answer.
So our final answer is 99. We have solved 90 plus 9 equals 99 using multiple methods, and they all confirm the same result.