The correct option is A 31
Cost of one pen = ₹ 6.20
⇒ Cost of 5 pens = ₹ 6.20×5
Multiplying the numbers ignoring the decimal places we get:
=620 x 5 = 3100
When a decimal number is multiplied by a whole number, the resulting number will have as many decimal places as the initial decimal number.
∴ Cost of 6 pens is ₹31.