Addition involves finding the total of two or more numbers or amounts. There are different things you can use to help you add. You can use number lines, place value charts and place value counters.

When you estimate a number you decide approximately, or roughly, how big that number is. To estimate accurately, you need to have a good understanding of the value and order of numbers. A number line ...

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. This is a number line. Hmm. Where should these numbers go? Let's start with the number 50. It's right ...