How many trailing zeros are there in the number 3 4 × 4 5 × 5 6 ?
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Simple standard approach accounting for the multiples of 2 and 5.
3^4 x 4^5 x 5^6 = (3x4x5)^4 x 4^1 x 5^2 = 60^4 x 100 = 6^4 x 10^4 x 10^2 Hence, there are 6 trailing zéros
3 4 ∗ 4 5 ∗ 5 6 3 4 ∗ 4 4 ∗ 5 4 ∗ 4 1 ∗ 5 2 6 0 4 ∗ 1 0 0 Therefore, there are 6 trailing zero’s
What do you call a mushroom that likes to go to parties? Fungi
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Lol. Why is that the title though?
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Fungi = Funguy = 6 letters = 6 = Answer!
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@Harsh Shrivastava – True genius on this question
3^4=81, 4^5=1024, 5^6=15625. 81 1024 15625=3^4 4^5 5^6. These are the same. 3^4 4^5 5^6=3^3 3, 4^5=4^4 4, 5^6=5^5 5 So 27 3 256 4 3125 5 This is 1.296e+9
First 1 0 n = 2 n × 5 n so lets find them
We have find 4 5 which 4 = 2 2 and 5 6
Then we start:
4 5 × 5 6 = ( 2 2 ) 5 × 5 6 = 2 2 × 5 × 5 6 = 2 1 0 × 5 6 = 2 1 0 − 6 + 6 × 5 6 = 2 1 0 − 6 × 2 6 × 5 6 = 2 4 × ( 2 × 5 ) 6 = 2 4 × 1 0 6
So the number of zero digits is 6
2x5=10
Simple, but important.
You see, 5^6 is 6 fives, and 4^5 is 5 fours.
But one four is two twos.
So 4^5 is 10 twos.
That means there are 6 pairs of fives and twos multiplied together to be a ten
3^4x4^5x5^6
=3^4x4^4x5^4x4x5^2
=60^4x10^2
=6^2x10^2x6^2x10^2x10^2
Which is 10^2x10^2x10^2 and that is 10^6 so it has 6 zeroes.
It so happens that all the above expressions are square numbers as well as higher powers. The square roots of each part of the above equation are 9, 32 and 125, so we are looking at (9 x 32 x 125) x (9 x 32 x 125) = (288 x 125) x (288 x 125) = 36,000 x 36,000. In that final equation we are multiplying a number with three trailing zeros by itself, so we will have six trailing zeros at the end of our final sum. For the record one last (straightforward) calculation gives us 1,296,000,000 as the actual answer.
Relevant wiki: Trailing Number of Zeros
For trailing number of zeros, we need to find number of 10's we can get. For us, 3 4 is useless as it will not help in finding 10. Here, highest power of 2 → 2 1 0 . Also, highest power of 5 → 5 6 . So, we require to have highest number of 2 and 5. As a result we will take 2 6 × 5 6 = 1 0 6 . So, total number of trailing zeros are 6 .
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In the above multiplication, we have 4 5 = 2 1 0 and 5 6
So there are 10 of TWO and 6 of FIVE.
We also know that 2 × 5 = 1 0 is what account for a trailing zero. There are 6 of 2 × 5 in the above multiplication. Hence, there would be 6 trailing zero.