2. Natural Number The counting numbers 1, 2, 3, 4, … are called natural numbers.

3. Whole Number The natural numbers along with 0 are called whole numbers

4. Digits In Hindu-Arabic system of writing numbers, the ten symbols namely 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9 are called digits or figures.

5. Numeral A single digit or group of digits denoting a number is called a numeral. For example, 8; 3451 and 71563 are numerals.

6. Numeration Writing a number in words is called numeration.

7. Number Pattern Numbers can have some interesting patterns. Complete the table given alongside to find out for yourself. 9 + 1 = 10 99 + 1 = 100 999 + 1 =............. 9,999 + 1 =............. 99,999 + 1 =.............

8. Face Value The face value of a digit is the number or a symbol it represents irrespective of its position in the numeral. For example, the face value of ‘5’ in 3,76,451 as well as in 57,869 is 5.

9. Place Value The place value of a digit in a number is its face value multiplied by its position value in the place value chart. The place value of a digit depends on its position in the number. For example, the place value of ‘5’ in 6,285 is 5 × 1 = 5 and 5,41,008 is 5 × 1,00,000 = 5,00,000

10. Indian system of numeration In the Indian system of numeration commas are placed after 3 digits starting from the right. The other periods to the left of the ones period have two places each. 1,00,000.00

11. International system of numeration In the International system of numeration commas are placed after every 3 digits from the right.

12. Roman Numeral System The Roman numeral system uses seven basic symbols to represent numbers. I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1,000 We also follow certain rules specific to the Roman numeral system.

13. Roman Symbol

14. Standard Unit of measurement The standard unit of length is metre. There exist smaller as well as bigger units of length. Their relation are as follows: 1 centimetre (cm) = 10 millimetres (mm) 1 decimetre (dm) = 10 centimetres (cm) 1 metre (m) = 10 decimetres (dm) 1 decametre (dam) = 10 metres (m) 1 hectometre (hm) = 10 decametres (dam) 1 kilometre (km) = 10 hectometres (hm)

15. Mass The standard unit of mass is kilogram (kg). There exist smaller as well as bigger units of mass. Their relation are as follows: 1 centigram (cg) = 10 milligrams (mg) 1 decigram (dg) = 10 centigrams (cg) 1 gram (g) = 10 decigrams (dg) 1 decagram (dag) = 10 grams (g) 1 hectogram (hg) = 10 decagrams (dag) 1 kilogram (kg) = 10 hectograms (hg)

16. Capacity The standard unit of capacity is litre (L).There exist smaller as well as bigger units of capacity. Their relation is as follows: 1 centilitre (cL) = 10 millilitres (mL) 1 decilitre (dL) = 10 centilitres (cL) 1 litre (L) = 10 decilitres (dL) 1 decalitre (daL) = 10 litres (L) 1 hectolitre (hL) = 10 decalitres (daL) 1 kilolitre (kL) = 10 hectolitres (hL)