What is the value of 1/(1 + √2) + 1/(√2 + √3) + 1/(√3 + √4) + … + 1/(√15 + √16)?
Correct answer A. 3
Topic / 43 questions
Surds and Indices MCQs test the laws of exponents and roots, such as multiplying powers with the same base and simplifying negative or fractional powers. They appear in NTS, ECAT, SSC and bank aptitude papers. Each question has an instant answer, so you can check your simplification and learn the rules by heart.
Correct answer A. 3
Correct answer A. 125
Correct answer D. 27
Correct answer C. 1/c = 1/a + 1/b
Correct answer D. 3/2
Correct answer A. 1
Correct answer C. 21
Correct answer C. 5
Correct answer B. √7 + √5
Correct answer B. 8
Correct answer A. 3 + 2√2
Correct answer D. 18
Correct answer A. √11 − √10
Correct answer C. 1
Correct answer C. 8
Correct answer B. 3
Correct answer B. 2√3 − √6
Correct answer D. 1.414
Correct answer B. x
Correct answer B. 3²⁰
This Aptitude topic is built on a few laws of indices. When powers with the same base are multiplied, the exponents are added; when divided, they are subtracted; a power raised to another power has its exponents multiplied; and a negative exponent means the reciprocal. Questions ask you to simplify expressions such as 256 to the power 0.16 times 256 to the power 0.09, find unknown exponents in equations like 5 to the power a equals 3125, and evaluate decimals raised to negative fractional powers. Writing every number as a power of a small base is the fastest approach.
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The main laws are: a^m × a^n = a^(m+n), a^m ÷ a^n = a^(m minus n), (a^m)^n = a^(mn), a^0 = 1 for non-zero a, and a^(minus n) = 1 ÷ a^n. A fractional power such as a^(1/2) means the square root of a.
Because the bases are the same, add the exponents: 0.16 + 0.09 = 0.25. So the expression equals 256 to the power one quarter, which is the fourth root of 256. Since 4 to the power 4 is 256, the answer is 4.
Last reviewed October 2026