Saturday, April 1, 2017

CBSE Class 6 - Maths - CH1 - Knowing Your Numbers (NCERT Ex 1.3) (#cbsenotes)

Knowing Your Numbers 

CBSE Class 6 - Maths - CH1 - Knowing Your Numbers (NCERT Ex 1.3) (#cbsenotes)

CBSE Class 6 - Maths - CH1 - NCERT Ex 1.3 Answers


Q1. Estimate each of the following using general rule:
(a) 730 + 998 
(b) 796 – 314 
(c) 12,904 +2,888 
(d) 28,292 – 21,496


Answer:
(a) 730 round off to     700
998 round off to 1000
──────
Estimated sum =  1700
──────

(b) 796 round off to   800
314 round off to 300
──────
Estimated sum = 500
──────

(c) 12904 round off to 13000
2888 round off to   3000
──────
Estimated sum  = 16000
──────

(d) 28292 round off to      28000
21496 round off to  21000
 ──────
      Estimated difference = 7000
 ──────



Q2. Give a rough estimate (by rounding off to nearest hundreds) and also a closer estimate
(by rounding off to nearest tens) :
(a) 439 + 334 + 4,317
(b) 1,08,734 – 47,599
(c) 8325 – 491
(d) 4,89,348 – 48,365

Answer:
(a) 439 round off to     400
334 round off to   300
4317 round off to 4300
──────
Estimated sum =   5000
      ──────


(b) 108734 round off to 108700
47599 round off to   47600
──────
    Estimated difference = 61100
        ──────

(c) 8325 round off to 8300
491 round off to                500
      ──────
Estimated difference =   7800
      ──────

(d) 489348 round off to 489300
48365 round off to    48400
──────
Estimated difference =    440900
       ──────


Q3. Estimate the following products using general rule:
(a) 578 × 161 
(b) 5281 × 3491 
(c) 1291 × 592 
(d) 9250 × 29

Answer:

(a) 578 × 161
578 round off to 600
161 round off to 200
The estimated product = 600 × 200 = 1,20,000

(b) 5281 × 3491
5281 round of to 5,000
3491 round off to 3,500
The estimated product = 5,000 × 3,500 = 1,75,00,000

(c) 1291 × 592
1291 round off to 1300
592 round off to 600
The estimated product = 1300 × 600 = 7,80,000

(d) 9250 × 29
9250 round off to 10,000
229 round off to 30
The estimated product = 10,000 × 30 = 3,00,000

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