0.4 is a repeating decimal explain how this happened

0.4 is equivalent to 4/10, which can be simplified to 2/5. When we divide 2 by 5, we get a decimal that repeats the digit 4. This happens because the number 5 in the denominator cannot be evenly divided into 2, resulting in a recurring decimal.

2.51 is a reating decimal explaine how that happend

When we express 2.51 as a fraction, we have:

2.51 = 251/100

To convert this fraction into a recurring decimal, we divide 251 by 100:
251 ÷ 100 = 2.51

The decimal representation of 2.51 does not repeat as there are no recurring or repeating digits in the decimal expansion.