1. 138 ≈ 140 

    62  ≈ 60

    67  ≈ 70

2.  7842 ≈ 7800

   89367 ≈ 89400

  917527≈ 917500

3. a ) 3,141592653589793238462643 ≈ 3,14

    b ) 3,141592653589793238462643 ≈ 3,1416

    c ) 3,141592653589793238462643 ≈ 3,141593

    d ) 3,141592653589793238462643 ≈ 3,141592653599

4. a ) 79,3826 ≈ 79,383

    b ) 79,3826 ≈ 79,38

    c ) 79,3826 ≈ 79,4

5. a ) 7,923 ≈ 7.92

   b ) 7,9238 ≈ 7,92

   c ) 17,418 ≈ 17,42

   d ) 79,1364 ≈ 79,14

   e ) 50,401 ≈ 50,40

   f ) 60,996 ≈ 61,00

   g ) 0,158 ≈ 0,16

   h ) 0,196 ≈ 0,20

1)$138$ $\approx$ $140;$    $62$ $\approx$ $60;$    $67$ $\approx$ $70.$

2)$7842$ $\approx$ $7800;$    $89367$ $\approx$ $89400;$    $917527$ $\approx$ $917500$

3)$\pi$ $\approx$ $3,141592653589793238462643$

$a.\pi$ $\approx$ $3,14$

$b.\pi$ $\approx$ $3,1416$

$c.\pi$ $\approx$ $3,141593$

$d.\pi$ $\approx$ $3,1415926535810$ 

4)

$a.79,3826\approx 79,383$

$b.79,3826\approx 79,38$

$c.79,3826\approx 79,4$ 

5)$a.7,923\approx 7,92$

$b.7,9238\approx 7,92$

$c.17,418\approx 11.42$

$d.79,1364\approx 79,14$

$e.50,401\approx 50,40$

$f.60,996\approx 61,00$

$g.0,158\approx 0,16$

$h.0,196\approx 0,20$