A man has 2 bankcards, each with a 4 digit number. The 1st number is 4 times the 2nd. The 1st number is the reverse of the 2nd. What is the first number?

• 8712. You could use trial and error. The smaller number must start with a 1 or a 2 (otherwise the bigger number would have 5 digits) so the bigger number must end with 1 or 2. Actually, it has to be 2, because the bigger number must be a multiple of 4. Consequently the numbers are 2**8 and 8**2. The digit after the 2 has to be small (because 4 times the number is less than 10)
• 12 years agoHelpfull: Yes(2) No(1)
• First number is 8712
  As 2178*4= 8712
• 12 years agoHelpfull: Yes(1) No(1)