Build numbers from ones, tens, hundreds and thousands. Ten blocks of one kind make one block of the next.
🔟 Decimals →0 ≠ 53
Use + and − under each column.
0
When a column gets to 10, swap them for 1 block in the next column to the left.
Place value means a digit is worth more or less depending on where it sits. In 347 the 3 is worth 300, the 4 is worth 40 and the 7 is worth 7. Building the number from blocks shows why.
A cube for 1, a rod of ten cubes for 10, a flat of ten rods for 100 and a big cube for 1000. Ten of one block always make one of the next, which is the whole idea of our number system.
Taking away often needs it: to work out 52 − 7 you break one of the tens into ten ones. Doing it with blocks first makes exchanging (or borrowing) in written subtraction make sense.
Children of about 5 or 6 can start with tens and ones up to 99. Hundreds come at about 7 and thousands at about 8 or 9, along with rounding and comparing numbers.