What number am i?

Question

2 I am a 7-digit odd number. The 3 stands for 3 tens. The product of the digit in the millions place and the digit in the tens place is 15. The value of the digit 9 is 90 000. The sum of all digit in the number is 30. The digit in the thousands place is twice greater than the digit in the hundreds place. The digit 8 is in the thousands place. The difference between the digit in the millions place and the digit in the ones place is 4. What number am I?

Answer 1

Let ABCDEFG represent the 7-digit odd number: G is odd, so G=1, 3, 5, 7 or 9.

3 stands for 3 tens: F=3.

The product of the digit in the millions place and the digit in the tens place is 15:

AF=15, A=15/F=5.

The value of the 9 digit is 90000: C=9.

Sum of all digits=30: A+B+C+D+E+F+G=30=5+B+9+D+E+3+G, B+D+E+G=30-17=13.

The digit 8 is in the thousands place: D=8.

This digit is twice the digit in the 100s place: 8=2E, E=8/2=4. D+E=12, B+G=13-12=1.

The difference between the digit in the millions place and ones place is 4: A-G=4, G=5-4=1.

B+G=1, B=1-G=1-1=0.

The number is 5098431.