Question 10 - Mix Questions (Page 20 & 21) - Chapter 1 Class 7 - Large Numbers Around us (Ganita Prakash)

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Question 10 You are given some number cards; 4000, 13000, 300, 70000, 150000, 20, 5. Using the cards get as close as you can to the numbers below using any operation you want. Each card can be used only once for making a particular number. (a) 1,10,000: Closest I could make is 4000 × (20 + 5) + 13000 = 1,13,000 (b) 2,00,000: (c) 5,80,000: (d) 12,45,000: (e) 20,90,800:Let’s try one by one Available Cards: 4000, 13000, 300, 70000, 150000, 20, 5 (a) 1,10,000: Your calculation: 4000×(20+5)+13000 =4000×25+13000 =100000+13000=113,000 Difference: 113,000−110,000=3,000 (b) 2,00,000: Calculation: 150000+70000−(4000×5) =220000−20000 =200,000 Difference: 200,000−200,000=0 (Exact!) (c) 5,80,000: Calculation: 70000×5+150000+(4000×20) =350000+150000+80000 =500000+80000=580,000 Difference: 580,000−580,000=0 (Exact!) (d) 12,45,000: Calculation: 4000×300+70000−(150000/5) =1200000+70000−30000 =1270000−30000=1240000 Difference: 1245000−1240000=5,000 (Another equally close option is 70000×20−150000=1400000−150000=1250000, which is also 5,000 away.) (e) 20,90,800: Calculation: (70000−4000)×20+150000×5+13000+300 =66000×20+750000+13000+300 =1320000+750000+13000+300 =2070000+13000+300 =2083000+300=2083300 Difference: 2090800−2083300=7,500