RRB NTPC CBT-1 Math Shortcuts: 10 Formula Tricks to Solve in 20 Seconds

In RRB NTPC CBT-1, you get 90 minutes for 100 questions. Speed in arithmetic is the single biggest factor distinguishing qualifiers from the rest.

Trick 1: 2-Year CI and SI Difference

When difference between Compound Interest and Simple Interest for 2 years is given:

$$\text{Difference (D)} = P \times \left(\frac{R}{100}\right)^2$$

Trick 2: Trains Crossing a Moving Object / Platform

$$\text{Time} = \frac{\text{Length of Train} + \text{Length of Platform}}{\text{Speed in m/s}}$$

Remember to convert km/h to m/s by multiplying with $5/18$.