During my exam preparation I faced many challenges for boosting my calculation speed in Quantitative Aptitude. But after practice I have improved my calculation speed. Here some steps have been mentioned which I followed -
1- Learn table , squares, cubes and its roots.
2- Try to sum , division, multiplication , subtraction in mind without using pen .
3- Use any quiz app daily for 10 -15 minutes.
4- If you are free then randomly choose some numbers and calculate it.
these some points which may help you to enhance your speed.
