You can show whole numbers as fractions on a number line. The number 3 is any fraction with a top number (numerator) that is 3 times the denominator. The number 7 is any fraction with a top number 7 times the denominator. The whole number 4 is any fraction with a top number 4 times the denominator.
Let's try writing the simplest fractions for the whole numbers on the number line. For 1, we'll write 
. For 2, we'll write 
. For 3, we'll write 
, and so on.
All of the fractions have 1 in the denominator. The whole number times the denominator 1 equals the top number.
Let's try a number line with a denominator of 5. What fraction with this denominator is equal to the whole number 2? Remember-multiply 2 times the denominator to get the top number. In this case, multiply 2 x 5 = 10. You should have come up with 
.
If we want to show thirds on a number line, we use 3 as the denominator. What's the top number of the fraction for 4 wholes on the number line? Multiply 4 times the denominator 3, and you get 12. The fraction 
is equal to four wholes. The top number for three wholes is 9. The fraction 
is equal to three wholes. You can change the number line so that each whole number is shown in thirds.
