What is the remainder obtained when 1010 + 105 – 24 is divided b...
Given:
To find: The remainder when 1010 + 105 – 24 is divided by 36
Approach:
- Let the required remainder be r. This means, we will be able to write:
1010 + 105 – 24 = 36k + r, where quotient k is an integer and 0 ≤ r < 36
The above expression is our GOAL expression. We’ll try to simplify the dividend 1010 + 105 – 24 till it is comparable to our GOAL expression, and then, by comparison, we’ll be able to find the value of r.
Working Out:
- 1010 + 105 – 24 = 1005 + 1002*10 – (36 – 12)
- =(36*3 – 8)5 + (36*3 – 8)2*10 – 36 + 12
- Now, from Binomial Theorem, we know that every term in the expansion of (36*3 – 8)5 will be divisible by 36, except the last term, and the last term will be (-8)5
- So, we can write: (36*3 – 8)5 is of the form 36a + (-8)5, where 36a is a catch-all term conveying that all the other terms in this expansion are divisible by 36
- Similarly, every term in the expansion of (36*3 – 8)2 will be divisible by 36 except the last term, and the last term will be (-8)2
- So, we can write: (36*3 – 8)2 = 36b + (-8)2
- So, the given expression simplifies to:
- {36a + (-8)5 } + {36b + (-8)2}*10 – 36 + 12
- = (36a + 360b – 36) + (-85 + 640 + 12)
- = (36a + 360b – 36) + (-85+ 652)
- = (36a + 360b – 36 + 648) + (-85+ 4)
- = (36a + 360b – 36 + 36*18) + (-85+ 4)
- The above expression is not comparable to our GOAL expression because the term -85 in it is still unresolved. Do we need to calculate the value of -85 to answer this question? No. We only need to express it in terms of 36. Once again, we’ll use Binomial Theorem to do so:
- -85 = -8(82)2 = -8(64)2 = -8(36*2 – 8)2
- Every term in the expansion of (36*2 – 8)2 will be divisible by 36 except the last term. The last term will be (-8)2 = 64
- So, the expression (36*2 – 8)2 can be written as: 36c + 64
- So, -8(36*2 – 8)2 = -8(36c + 64)
- =-8(36c + 36*2 – 8)
- = (-8*36c – 8*36*2) + 64
- So, the given expression simplifies to: (36a + 360b – 36 + 72) + {(-8*36c – 8*36*2) + 64} + 4
- = (36a + 360b – 36 + 72 – 8*36c – 8*36*2) + 68
- =(36a + 360b – 36 + 72 – 8*36c – 8*36*2 + 36) + 32
- Now, the above expression is exactly comparable to our GOAL Expression: 36k + r
- So, by comparison, we can say that Remainder r = 32
Looking at the answer choices, we see that the correct answer is Option E
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What is the remainder obtained when 1010 + 105 – 24 is divided b...
To find the remainder when 1010, 105, and 24 are divided by 36, we can perform the division and observe the remainder.
Dividing 1010 by 36:
When we divide 1010 by 36, we get a quotient of 28 and a remainder of 22.
Dividing 105 by 36:
When we divide 105 by 36, we get a quotient of 2 and a remainder of 33.
Dividing 24 by 36:
When we divide 24 by 36, we get a quotient of 0 and a remainder of 24.
Now, let's perform the division again but with the remainders.
Dividing 22 by 36:
When we divide 22 by 36, we get a quotient of 0 and a remainder of 22.
Dividing 33 by 36:
When we divide 33 by 36, we get a quotient of 0 and a remainder of 33.
Dividing 24 by 36:
When we divide 24 by 36, we get a quotient of 0 and a remainder of 24.
Summing the remainders:
To find the remainder when the sum of the three numbers is divided by 36, we sum the remainders obtained in each division: 22 + 33 + 24 = 79.
Reducing the remainder:
Since the remainder obtained (79) is greater than the divisor (36), we need to reduce it. We can do this by repeatedly subtracting the divisor until we obtain a remainder less than the divisor.
79 - 36 = 43
43 - 36 = 7
The remainder after reducing is 7.
Therefore, the remainder obtained when 1010, 105, and 24 are divided by 36 is 7.
Hence, the correct answer is option E.
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