To find the units digit of 399 the question being asked is:
What is (399) MOD 10?
This does not necessitate evaluation of 399 before the modulus is done, as it can be done whenever it is possible during the multiplication as any multiple of 10 multiplied by 3 is still a multiple of 10.
The first few powers of 3 modulus 10 are:
31 MOD 10 = 3
32 MOD 10 = (3 x 31) MOD 10 = (3 x 3) MOD 10 = 9
33 MOD 10 = (3 x 32) MOD 10 = (3 x 9) MOD 10 = 27 MOD 10 = 7
34 MOD 10 = (3 x 33) MOD 10 = (3 x 7) MOD 10 = 81 MOD 10 = 1
35 MOD 10 = (3 x 34) MOD 10 = (3 x 1) MOD 10 = 3
36 MOD 10 = (3 x 35) MOD 10 = (3 x 3) MOD 10 = 9
At this point, it can be seen that the answer is a repeating pattern of 3, 9, 7, 1, 3, 9, ...
So we need the 99th element of this pattern.
The pattern is a repeat of 4 digits, so we calculate 99 MOD 4 = 3. So the 3rd element of the repeating part is the answer: 7.
(If the power MOD 4 had been 0, it would have been the 4th element of the pattern: 1)
The unit digit of 3127173 is the unit digit of 7173. The other digits of 3127 are multiples of 10 and so they cannot contribute to the unit digit. Now the unit digits of the powers of 7 are Power -- Unit digit 0 -- 1 1 -- 7 2 -- 9 3 -- 3 4 -- 1 and you are back into the loop (of 1-7-9-3). So, you only need consider 7 to the power 173 modulo 4. That is, the remainder when 173 is divided by 4. 173 = 1 mod 4 So the unit digit of 3127173 is the same as the unit digit of 7173 which is the unit digit of 71 which is 7.
A smaller 3 digit number or a 2 digit number (99).
Any digit in the tens or higher place has no influence on the answer. So it is the unit digit of 4*9*3*6 = unit digit of 6*3*6 = unit digit of 8*6 = 8
IN WHOLE NUMBER FIRST DIGIT IS 0 SO THAT WE HAVE TO SUM 1-98 NUMBERS :-SUM OF 1-10 IS 55 SO IN SUM OF EACH 11-20,21-30......THE UNIT DIGIT WILL COME 5 SO FOR THAT WE MULTIPLY 5*9+1+2+3+4+5+6+7+8 AFTER THIS CALCULATION WE GOT 1 AS A UNIT DIGIT NUMBER
No. When adding the smallest 2 digit number (= 10) to the smallest 2 digit number (again, 10) the result is a 2 digit number (10 + 10 = 20). When adding the largest 2 digit number (= 99) to the largest 2 digit number (again, 99) the result is a 3 digit number (99 + 99 = 198). As you can see, you'll either get a 2 or 3 digit number, but never a 4 digit number.
The unit digit of 3127173 is the unit digit of 7173. The other digits of 3127 are multiples of 10 and so they cannot contribute to the unit digit. Now the unit digits of the powers of 7 are Power -- Unit digit 0 -- 1 1 -- 7 2 -- 9 3 -- 3 4 -- 1 and you are back into the loop (of 1-7-9-3). So, you only need consider 7 to the power 173 modulo 4. That is, the remainder when 173 is divided by 4. 173 = 1 mod 4 So the unit digit of 3127173 is the same as the unit digit of 7173 which is the unit digit of 71 which is 7.
Well, isn't that a happy little math problem! When we look at the unit digit of powers of numbers, we focus on the cyclical pattern they follow. The unit digit of 3 raised to any power follows a pattern: 3, 9, 7, 1, and then repeats. So, to find the unit digit of 3 to the power of 34 factorial, we look for the remainder when 34 factorial is divided by 4, which is 2. Therefore, the unit digit of 3 to the power of 34 factorial is 9.
A smaller 3 digit number or a 2 digit number (99).
Because after 99 comes a hundred which is a 3 digit number.
Any digit in the tens or higher place has no influence on the answer. So it is the unit digit of 4*9*3*6 = unit digit of 6*3*6 = unit digit of 8*6 = 8
IN WHOLE NUMBER FIRST DIGIT IS 0 SO THAT WE HAVE TO SUM 1-98 NUMBERS :-SUM OF 1-10 IS 55 SO IN SUM OF EACH 11-20,21-30......THE UNIT DIGIT WILL COME 5 SO FOR THAT WE MULTIPLY 5*9+1+2+3+4+5+6+7+8 AFTER THIS CALCULATION WE GOT 1 AS A UNIT DIGIT NUMBER
99 is odd and if you added one more it would be 3 digit.
No. When adding the smallest 2 digit number (= 10) to the smallest 2 digit number (again, 10) the result is a 2 digit number (10 + 10 = 20). When adding the largest 2 digit number (= 99) to the largest 2 digit number (again, 99) the result is a 3 digit number (99 + 99 = 198). As you can see, you'll either get a 2 or 3 digit number, but never a 4 digit number.
99
It is the 3.
3 to a power divisible by 4 will have a units digit of 1.The powers of 3 are 3, 9, 27, 81 ... obviously, the next one will have a units digit of 1x3 or 3, the next one will have a units digit of 3x3 or 9, the next one will have a units digit of 7 (because 9x3 is 27), the next one will have a units digit of 1 (because 7x3 is 21), and then the cycle starts over with a units digit of 3 again.
The largest 2-digit number is 99. When 99 is divided by 4, the quotient is 24 with a remainder of 3. This is because 99 divided by 4 equals 24 with a remainder of 3.