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Lesson 3 of 6

Using the fx-991CW for number and algebra

I can use the fx-991CW to perform calculations with numbers and solve equations numerically.

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Lesson 3 of 6
New
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Using the fx-991CW for number and algebra

I can use the fx-991CW to perform calculations with numbers and solve equations numerically.

Lesson details

Key learning points

  1. Some calculators can perform more than just basic calculations.
  2. The fx-991CW can convert between different formats for values.
  3. The fx-991CW can solve equations numerically.

Keywords

  • Prime factor - Prime factors are the factors of a number that are, themselves, prime.

  • Equation - An equation is used to show 2 expressions that are equal to each other.

  • Simultaneous equations - Equations which represent different relationships between the same variables are called simultaneous equations.

  • Inequality - An inequality is used to show that one expression may not be equal to another.

Common misconception

Calculators can only be used to add, subtract, multiply or divide.

They can be used to perform basic calculations but they can also do so much more.

For more support with using the Casio fx-991CW, please visit the Casio website where there are more free resources and interactive guides to support use of this model.
Teacher tip

Equipment

Casio fx-991CW

Licence

This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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Prior knowledge starter quiz

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6 Questions

Q1.
A is a term which exactly divides another term.

Correct Answer: factor

Q2.
Select the prime factors of 14.

1
Correct answer: 2
Correct answer: 7
14

Q3.
A decimal is one that has an infinite number of digits after the decimal point.

Correct Answer: recurring

Q4.
An is used to show 2 expressions that are equal to each other.

Correct Answer: equation

Q5.
Equations which represent different relationships between the same variables are called equations.

Correct Answer: simultaneous

Q6.
An is used to show that one expression may not be equal to another.

Correct Answer: inequality

Assessment exit quiz

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6 Questions

Q1.
What does inputting a mixed number into the calculator and pressing ‘EXE’ return?

The same value but as a decimal
The same mixed number
Correct answer: The same value but as an improper fraction

Q2.
Which button is used to change freely between improper fractions and mixed numbers?

CATALOG
Correct answer: FORMAT
FUNCTION
TOOLS
VARIABLE

Q3.
Which of these shows the number 2 227 500 expressed in prime factor form?

$$2^2 \times 3^2 \times 5^4 \times 11$$
$$2^2 \times 3^2 \times 5^6 \times 11$$
Correct answer: $$2^2 \times 3^4 \times 5^4 \times 11$$
$$2^2 \times 3^4 \times 5^4 \times 11^2$$

Q4.
Use your calculator to solve $$x^2 + 6x + 8 > 3$$

$$−5 < x < −1$$
$$−5 > x > −1$$
Correct answer: $$−5 > x$$ , $$x > −1$$
$$−5 < x$$ , $$x < −1$$

Q5.
Use your calculator to solve $$x^2 + 12x - 15 < 4x + 5$$

Correct answer: $$−10 < x < 2$$
$$−10 > x > 2$$
$$−10 > x$$ , $$x > 2$$
$$−10 < x$$ , $$x < 2$$

Q6.
Use your calculator to solve $$a^2 - 12a + 11 = 0$$

Correct answer: $$a = 1$$ , $$a = 11$$
$$a = 3$$ , $$a = 4$$
$$a = -1$$ , $$a = -11$$
$$a = -3$$ , $$a = -4$$

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