These 25, 26, 27, 28 and 29 are five consecutive natural numbers; The tolerance between them is1; The sum of these five numbers is the sum of arithmetic progression; In addition, the ten digits of these five numbers are all 2.

There are many ways to sum, and only three are introduced for reference:

1, extract the sum of the same integer plus single digits.

25+26+27+28+29

=20×5+5+6+7+8+9

= 100+35

= 135

2, take the middle number multiplied by the number of items.

25+26+27+28+29

=27×5

= 135

3. Calculate with the sum formula of arithmetic sequence.

25+26+27+28+29

=(25+29)×5÷2

= 135