Sum of the digits

How many are two-digit natural numbers that have the sum of the digits 9?

Result

n =  9

Solution:




Our examples were largely sent or created by pupils and students themselves. Therefore, we would be pleased if you could send us any errors you found, spelling mistakes, or rephasing the example. Thank you!





Leave us a comment of this math problem and its solution (i.e. if it is still somewhat unclear...):

Showing 0 comments:
1st comment
Be the first to comment!
avatar




Following knowledge from mathematics are needed to solve this word math problem:

Next similar math problems:

  1. Digits
    pin_keyboard How many odd four-digit numbers can we create from digits: 0, 3,5,6,7?
  2. Mystery number
    numbers2_38 A mystery number is between 800 and 920. No digits are the same. The difference of the number is 5. What is the mystery number?
  3. Divisibility 2
    divisors How many divisors has integer number 13?
  4. Gloves
    rukavice_1 Petra has ten pairs of gloves in the closet. Six pairs are blue, 4 pairs are yellow. How many pieces of gloves need to be pulled out at least when she pull them out in the dark and want to have one complete one color pair?
  5. Popsicles
    nanuky Francis went to buy ice lollies. If he buy 8 popsicles he missed 4 USD. When he buy 7 popsicles, got back 1 USD. How many USD was a popsicle?
  6. Rings - intersect
    venn_1 There are 15 pupils on the sporting ring. 10 pupils go to football, 8 pupils go to floorball. How many pupils go to both rings at the same time?
  7. Unknown number 16
    numbers_35 My number's tens is three times more then ones My number's ones is twice the number of thousands and my number's hundreds is half the number of of tens. I have two ones. which number am I?
  8. Write decimals
    numbers_34 Write in the decimal system the short and advanced form of these numbers: a) four thousand seventy-nine b) five hundred and one thousand six hundred and ten c) nine million twenty-six
  9. Roman numerals
    roman_1 Write numbers written in Roman numerals as decimal.
  10. Seven times
    numberline_12 Which number seven times is just as higher as 27, how much is smaller than 29?
  11. Division
    numbers_36 Which number in division 16 give 12 and the rest 3?
  12. Subtraction
    plusminus_1 Test what do you know about the subtraction of two numbers: a) make a difference if the minuend 4,307,288 and subtrahend is 472008 b) minuend is 4000 more than subtrahend. What's the difference? c) the difference is 38900 less than the minuend. What is th
  13. Primes 2
    prime_table Which prime numbers is number 2025 divisible?
  14. Addition of Roman numbers
    roman Added together and write as decimal number: LXVII + MLXIV
  15. Perpetrator
    snehulaci The perpetrator is a number that is smaller than the number 80. It is a multiple of five and it is odd. If we added up the tens and ones of this number we get number 8.
  16. Number
    num Determine unknown number if you know that difference between five times and triple of number is 42.
  17. Cages
    guineapig Honza had three cages (black, silver, gold) and three animals (guinea pig, rat and puppy). There was one animal in each cage. The golden cage stood to the left of the black cage. The silver cage stood on the right of the guinea pig cage. The rat was in the