Alarm clock

The old watchmaker has a special digital alarm in its collection that rings whenever the sum of digits of the alarm is equal to 21. Find out when the alarm clock will ring. What is their number? List all options ...

Result

n =  16

Solution:  Leave us a comment of this math problem and its solution (i.e. if it is still somewhat unclear...): Be the first to comment! To solve this verbal math problem are needed these knowledge from mathematics:

See also our variations calculator. Would you like to compute count of combinations?

Next similar math problems:

1. The largest number Find the largest integer such that: 1. No figures is not repeat, 2. multiplication of every two digits is odd, 3. addition all digits is odd.
2. Decide The rectangle is divided into seven fields. On each box is to write just one of the numbers 1, 2 and 3. Mirek argue that it can be done so that the sum of the two numbers written next to each other was always different. Zuzana (Susan) instead argue that.
3. Perpetrator 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.
4. Foot in bus It was 102 people on the bus. 28 girls had two dogs. A 11 girls had one dog. At the next stop seceded 5 dogs (even with their owners). They got two boys together with three dogs. The bus drove one driver. How many foot were in bus?
5. Write decimals 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
6. To improve To improve her handwriting Paula practices writing the numbers 1 to 200 in words. How many times will she have written the word "one" in all?
7. Cages 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
8. Addition of Roman numbers Added together and write as decimal number: LXVII + MLXIV
9. Roman numerals Write numbers written in Roman numerals as decimal.
10. Number train The numbers 1,2,3,4,5,6,7,8 and 9 traveled by train. The train had three cars and each was carrying just three numbers. No. 1 rode in the first carriage, and in the last carriage was all odd numbers. The conductor calculated sum of the numbers in the first
11. Charles Bridge Charles Bridge was 15 times older than Frantův bridge from 1900 in 1931. How old is the Charles Bridge?
12. Equation algebraogram Solve the equation: oco + ivo = cita How much has the task of solutions? Daddy is a 46 year old and son is at age of 16. When (which year) was/will daddy 5 times more years than his son? Three elephants eat three piles of hay in 150 minutes. For how long does 96 elephants eat  96 stacks of hay? Table with numbers 3x3 in the first row 66,24,33 in the second row 57,? 19 in the third row 18,45,60 What number comes ar mark ?. Maybe the numbers: 22,46,45,47 16.2 days ..... how many hours is it? In leap years was 53 Sundays. On what day of the week fell to Christmas Day?