If a is a three digit number, now put 1 to the right of it to get a four digit number, which is () A. 1000a+1B. 100a+1C. 10a+1D. a+1

If a is a three digit number, now put 1 to the right of it to get a four digit number, which is () A. 1000a+1B. 100a+1C. 10a+1D. a+1

This four digit number can be expressed as 10A + 1

Solving multiple solutions to one problem with one variable linear equation 5x + 15 = 25
Seek a variety of solutions!

5x+15=25
x+3=5
x=2
5x+15=25
5x=10
x=2

If there is a two digit number, the number on the tenth digit is 5 times larger than the number on the single digit, and the two digit number is 5 times larger than the sum of the two digits, find the two digit number

Let X be the single digit, then x + 5 is the ten digit. From the meaning of the question, 10 (x + 5) + x = 8 [x + (x + 5)] + 5, the solution is: x = 1, then the two digit is 61