When we add we count up. We have  triangles in the first box, and then  triangles in the second box. In total we have  triangles. If you start at  on a number line and count up , you have .

We have  triangles and we want to subtract  triangle, which means the same thing as take them away. We can cross off the  triangle that we are subtracting, and count the number that we have left. In this case we have  triangles left. Subtraction is like counting backwards. We can start at  and count back .

We have  triangles and we want to subtract  triangle, which means the same thing as take them away. We can cross off the  triangle that we are subtracting, and count the number that we have left. In this case we have  triangles left. Subtraction is like counting backwards. We can start at  and count back .

We have  triangles and we want to subtract  triangle, which means the same thing as take them away. We can cross off the  triangle that we are subtracting, and count the number that we have left. In this case we have  triangles left. Subtraction is like counting backwards. We can start at  and count back .

We have  triangles and we want to subtract  triangle, which means the same thing as take them away. We can cross off the  triangle that we are subtracting, and count the number that we have left. In this case we have  triangles left. Subtraction is like counting backwards. We can start at  and count back .

We have  triangles and we want to subtract  triangle, which means the same thing as take them away. We can cross off the  triangle that we are subtracting, and count the number that we have left. In this case we have  triangles left. Subtraction is like counting backwards. We can start at  and count back .

We have  triangles and we want to subtract  triangle, which means the same thing as take them away. We can cross off the  triangle that we are subtracting, and count the number that we have left. In this case we have  triangle left. Subtraction is like counting backwards. We can start at  and count back .

We have  triangle and we want to subtract  triangle, which means the same thing as take it away. We can cross off the  triangle that we are subtracting, and count the number that we have left.In this case we have no triangles left. Subtraction is like counting backwards. We can start at  and count back .

We have  triangles and we want to subtract  triangle, which means the same thing as take them away. We can cross off the  triangle that we are subtracting, and count the number that we have left. In this case we have  triangles left. Subtraction is like counting backwards. We can start at  and count back .

We have  triangles and we want to subtract  triangle, which means the same thing as take them away. We can cross off the  triangle that we are subtracting, and count the number that we have left. In this case we have  triangles left. Subtraction is like counting backwards. We can start at  and count back .