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The value of 27 3 - 22 3 is:
9035
8823
8923
8888
9035
Check the unit digit: 273 ends in 3 (73=343) and 223 ends in 8 (23=8). The difference must end in 13−8=5. Only Option A ends in 5.
We are given two numbers, 27 and 22, and we need to find the difference between their cubes: 27³ - 22³.
a3−b3=(a−b)(a2+ab+b2)
Check the unit digit: 273 ends in 3 (73=343) and 223 ends in 8 (23=8). The difference must end in 13−8=5. Only Option A ends in 5.
Students often miscalculate large cubes (272727 = 19683 and 222222 = 10648) leading to simple arithmetic errors under pressure.
Identify values and formula
Set a=27 and b=22. Use the difference of cubes identity to simplify the calculation.
a3−b3=(a−b)(a2+ab+b2)
Substitute the values
Substitute a=27 and b=22 into the formula. First, calculate the difference: 27−22=5.
273−223=(27−22)(272+27×22+222)
Calculate the squares and product
Calculate 272=729, 222=484, and 27×22=594. Then sum these values: 729+594+484=1807.
1807×5=9035
A is correct because the application of the identity 273−223=(27−22)(272+27×22+222) yields 5×1807=9035.
Understanding the algebraic expansion of cubes is essential for high-speed calculation in Quantitative Aptitude, often appearing in simplification questions in SSC and banking exams.