No.2 pencils are widely used, but you may not know what the number actually refers to. This video explains how pencils developed into their modern form and the significance of the labeled numbers.

25 has 2 tens and 5 ones so we add 2 packets of pencils to the tens column and 5 marbles to the ones column. Now let's add the second number to the place value chart. 33 has 3 tens and 3 ones so ...