Expanded form shows how each digit contributes to a whole number. In the number 47,306, the 4 is worth 40,000 because it sits in the ten-thousands place, while the 3 is worth 300 because it sits in the hundreds place. Writing those contributions separately makes place value visible.
This calculator accepts a nonnegative whole number of up to 15 digits. It can show the original number, factor form such as 4 × 10,000, or powers-of-ten form such as 4 × 104. Zero digits still hold their places, but their zero-value terms are left out of the displayed sum.