Consider a number 235, where last digit is the sum of first two digits i.e. 2 + 3 = 5.
How many such 3-digit numbers are there?

• its a very long it follow a series -------
  when last digit is 1----- 101------------------------------------------1
  when last digit is 2-----202,112--------------------------------------+2
  when last digit is 3-----303,213,123,---------------------------------+3
  when last digit is 4-----404,134,314,224,-----------------------------+4
  so series as follow 1+2+3+4+5+6+7+8+9=9/2(1+9)=45
• 13 years agoHelpfull: Yes(11) No(0)
• Ans: 45
  101,112,123,134,145,156,167,178,189,202,213,224,235,246,257,268,279,303,314,325,,336,347,358,369,404,415,426,437,448,459,505,516,527,538,549,606,617,628,639,707,718,729,808,819,909
  
  
  
• 14 years agoHelpfull: Yes(4) No(2)
• 45
  there are 9 such numbers between 100 t0 200 and 8-(201-300),7-(301-400)...like this total 45
• 14 years agoHelpfull: Yes(1) No(0)
• 45
• 14 years agoHelpfull: Yes(0) No(0)
• it is undefind bcz we have lot of num like that
• 13 years agoHelpfull: Yes(0) No(0)