13 = 10 + 3
Let's see what makes the number thirteen.
Here are ten dots. Let's count them together.
One, two, three, four, five, six, seven, eight, nine, ten! Ten ones make one ten.
Now look! Here are three more dots.
We had one group of ten.
And three more ones.
Ten plus three is thirteen.
Thirteen is one ten and three ones. You did it!