Money and Time

Overview

Money and Time is a fundamental topic in CG TET Paper I Mathematics that tests a candidate's ability to perform everyday calculations involving Indian currency and time measurement. This topic directly connects classroom mathematics to real-life situations, making it essential for primary-level teaching.

In the CG TET exam, questions typically involve currency conversion, addition and subtraction of money amounts, calculating total cost or change, reading clocks, converting time units, and solving problems related to calendars and duration. The pedagogy aspect expects teachers to understand how children develop concepts of money and time through concrete experiences before moving to abstract calculations.

Mastery of this topic requires comfort with decimal operations (since rupees and paise work like decimals), understanding of the 12-hour and 24-hour clock systems, and familiarity with calendar patterns including leap years.

Key Concepts

• **Indian Currency System**: 100 paise = 1 rupee. Money is written as ₹X.YZ where X is rupees and YZ is paise (e.g., ₹45.75 means 45 rupees and 75 paise).

• **Place Value in Money**: When adding or subtracting money, align the decimal point. Paise are always written as two digits (₹5.05, not ₹5.5 for 5 rupees 5 paise).

• **Time Units Hierarchy**: 60 seconds = 1 minute; 60 minutes = 1 hour; 24 hours = 1 day; 7 days = 1 week; 12 months = 1 year.

• **12-Hour vs 24-Hour Clock**: 12-hour clock uses AM (midnight to noon) and PM (noon to midnight). 24-hour clock runs 00:00 to 23:59. To convert PM time to 24-hour format, add 12 to the hour (3:30 PM = 15:30).

• **Calendar Patterns**: Ordinary year has 365 days; leap year has 366 days. Leap year occurs when the year is divisible by 4, except century years must be divisible by 400.

• **Days in Months**: January-31, February-28/29, March-31, April-30, May-31, June-30, July-31, August-31, September-30, October-31, November-30, December-31. (Mnemonic: "30 days has September, April, June and November")

• **Duration Calculation**: To find time elapsed, subtract start time from end time. If minutes become negative, borrow 1 hour (60 minutes).

Formulas / Key Facts

| Conversion | Formula | |------------|---------| | Rupees to Paise | Rupees × 100 = Paise | | Paise to Rupees | Paise ÷ 100 = Rupees | | Hours to Minutes | Hours × 60 = Minutes | | Minutes to Seconds | Minutes × 60 = Seconds | | Days to Hours | Days × 24 = Hours |

**Key Facts to Remember:**

• 1 decade = 10 years; 1 century = 100 years