Now make the greatest and the smallest 4-digit numbers by using any one digit twice.

(a) 3 8 7 (b) 9 0 5 (c) 0 4 9 (d) 8 5 1 (Hint: Think in each case which digit will you use twice.)

Read these numbers. Write them using placement boxes and then write their expanded forms.

(i) 475320

(ii) 9847215

(iii) 97645310

(iv) 30458094

(a) Which is the smallest number?

(b) Which is the greatest number?

(c) Arrange these numbers in ascending and descending orders.

Express 23150 as a product of its prime factors. Is it unique?

Below is an equation that is not correct yet. By adding some plus signs and minus signs between the digits on the left side (without changes the order of the digits), the equation can be made correct. 123456789 = 100.

Question: How many different ways are there to make the equation correct? One way: 123 – 45 – 67 + 89 = 100. Can you give a systematic way to find answers ?123 + 45 –67 + 89 = 100, 1 + 2 – 3 + 4 + 5 + 6 + 78 + 9 = 100, 12 + 3 – 4 + 5 + 67 + 89 = 100, 1 + 2 + 34 – 5 + 67 – 8 + 9 = 100, 1 + 23 – 4 + 5 + 6 + 78 –9 = 100, 1 + 2 + 3 – 4 + 5 + 6 + 78 + 9 = 100, 12 –3 – 4 + 5 – 6 + 7 + 89 = 100, 12 + 3 4 + 5 –6 – 7 + 89 = 100, 1 + 23 – 4 + 56 + 7 + 8 + 9 = 100

Round off the given numbers to the nearest tens hundreds and thousands 75847 Tens _______ 75847 Hundreds _______ 75847 Thousands ________ 75847 Ten thousands ________