Class 9 Math: Number Systems Shortcut Methods & Tricks

In mathematics exams, time is your most valuable asset. Learning shortcut methods and mental calculation tricks for Number Systems can save you minutes per question, giving you ample time to review your answers and tackle difficult problems.

Syllabus Shortcut Methods

Butterfly Method for Fractions

To add a/b + c/d, cross multiply (ad + bc) to get the new numerator, and multiply denominators (bd) for the new denominator.

Divisibility Rule for 3 and 9

Sum the digits of the number. If the sum is divisible by 3 or 9, the entire number is divisible by 3 or 9.

When to Use (and Avoid) Shortcuts

Shortcuts are extremely useful for multiple-choice tests (MCQs), competitive exams like Olympiads, and double-checking your work. However, in standard school tests that score steps, you should always write out the full algebraic method. Writing shortcuts without detailing steps can result in losing partial credit.