General Science and Basic Mathematics: Class 6–10 science with clerical arithmetic
General Science and Basic Mathematics combines school-level science with the arithmetic used in clerical work: percentage, ratio, average, profit and loss, simple interest, time–speed–distance, LCM/HCF and simplification.
Science facts worth memorising
- SI units: force newton, work and energy joule, power watt, pressure pascal, frequency hertz.
- Human body: 206 bones in an adult, skin is the largest organ, 12 pairs of cranial nerves.
- Deficiency diseases: vitamin A night blindness, B1 beriberi, C scurvy, D rickets.
- Common names: baking soda NaHCO3, washing soda Na2CO3, quicklime CaO, plaster of Paris CaSO4·½H2O.
- Malaria is caused by Plasmodium and spread by the female Anopheles mosquito.
Worked example
A trader marks an item 25% above cost and allows a 20% discount. What is the result? Reasoning: take cost = ₹100. Marked price = ₹125. Discount is always calculated on the marked price, so selling price = 125 × 0.80 = ₹100. Selling price equals cost, so there is neither profit nor loss (0%). The tempting wrong answer, 5% profit, comes from subtracting 25 − 20.
Shortcuts and traps
- Convert speed with km/h × 5/18 = m/s.
- HCF × LCM = product of the two numbers - valid for exactly two numbers.
- Successive percentage change: net = a + b + ab/100.
- Always identify the base: discount uses marked price, profit uses cost price.
- Apply BODMAS strictly - brackets, 'of', division, multiplication, addition, subtraction.