Q. 109 B
Observe the following patterns and fill in the blanks to make the statements true:
7 × 4 = 28
7 × 3 = _______ = 28 – 7
7 × 2 = __ __ = _______– 7
7 × 1 = 7 = _______ – 7
7 × 0 = ______ = ______ –_______
7 × – 1 = –7 = ______ – _______
7 × – 2 = _____ = _____ – ______
7 × – 3 ______ = ______ – _______
Answer :
In order to fill these blanks, you need to identify the pattern.
Given is,
7 × 4 = 28
This can also be written as:
7 × 4 = 28 = 35 – 7
⇒ 7 × 4 = 28 = (7 × 5) – 7 …(i)
Now, note the equation in second line:
7 × 3 = ___ = 28 - 7
Here, the blank can be filled by simple multiplication of 7 by 3.
⇒
⇒ 7 × 3 = 21 = (7 × 4) – 7 ...(ii)
Now, note the equation in third line:
7 × 2 = ___ = _____ - 7
Here, the blank can be filled by simple multiplication of 7 by 2.
Note the pattern in the bolded equation of (i) and (ii),
(7) remains same, but (7 × 5) and (7 × 4) are in series.
⇒
⇒ ...(iii)
Now, note the equation in fourth line:
7 × 1 = 7 = ____ - 7
Note the pattern in the bolded equations of (i), (ii) and (iii),
(7) remains same, but (7 × 5), (7 × 4) and (7 × 3) are in series.
⇒
⇒ …(iv)
Now, note the equation in fifth line:
7 × 0 = ___ = ___ - ___
Here, the first blank can be filled by simple multiplication of 7 by 0.
Note the pattern in the bolded equations of (i), (ii), (iii) and (iv),
(7) remains same in the third blank, but (7 × 5), (7 × 4), (7 × 3) and (7 × 2) are in series.
⇒
⇒ …(v)
Now, note the equation in sixth line:
7 × -1 = -7 = ___ - ___
Note the pattern in the bolded equations of (i), (ii), (iii), (iv) and (v),
(7) remains same in the third blank, but (7 × 5), (7 × 4), (7 × 3), (7 × 2) and (7 × 1) are in series.
⇒
⇒ ...(vi)
Now, note the equation in seventh line:
7 × -2 = ___ = ___ - ___
Here, the first blank can be filled by simple multiplication of 7 by -2.
Note the pattern in the bolded equations of (i), (ii), (iii), (iv), (v) and (vi),
(7) remains same in the third blank, but (7 × 5), (7 × 4), (7 × 3), (7 × 2) and (7 × 0) are in series.
⇒
⇒ …(vii)
Now, note the equation in eighth line:
7 × -3 = ___ = ___ - ___
Here, the first blank can be filled by simple multiplication of 7 by -3.
Note the pattern in the bolded equations of (i), (ii), (iii), (iv), (v), (vi) and (vii),
(7) remains same in the third blank, but (7 × 5), (7 × 4), (7 × 3), (7 × 2), (7 × 0) and (7 × -1) are in series.
⇒
⇒ …(viii)
Thus, we have
7 × 4 = 28
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