This is one of the easiest activities to determine HCF in an engaging manner by using blocks. This activity is based on determining HCF by the common division method. As division means repeated subtraction, this activity focuses on the same. This activity can be carried out in the following steps :

1. Take a sheet of paper and some blocks.
2. Make two columns on the sheet of paper and write numbers on the top whose HCF is to be determined. For example, to find the HCF of 12 and 18, write 12 and 18 in each column.
3. Put the same number of blocks in each column.
4. Eliminate a smaller number of blocks from the larger number, and keep eliminating until the number of blocks is equal on both sides.
5. Initially, there were 12 blocks on one side and 18 blocks on the other. Eliminating smaller number (12) from the larger number (18), so 18 – 12 = 6.
6. Now, we have 12 in one column and 6 in the other, so by subtracting the smaller number 6 from the larger number 12, 12 – 6 = 6, we get 6 in both columns, which is the HCF of 12 and 18.

• HCF