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Civil Service Exam

Numerical Ability

"Beshy, huminga ng malalim. Math lang 'to! Hindi tayo papa-api sa numbers. Ready ka na ba maging Math Wizard? Tara, himayin natin!"

1. Basic Operations & PEMDAS (Order of Operations) 🧮

Beshy, bago tayo lumipad, matuto muna tayo lumakad. Ang math parang relationships, may sinusunod na order of priority. Wag kang basta-basta!

PEMDAS Rule:

  • Parenthesis (Unahin ang nasa loob ng brackets)
  • Exponents (Powers and roots)
  • Multiplication & Division (Left to Right!)
  • Addition & Subtraction (Left to Right!)

Example: 8 + 4 x 2 - 6 / 3

  • Multiply: 4 x 2 = 8. (Equation: 8 + 8 - 6 / 3)
  • Divide: 6 / 3 = 2. (Equation: 8 + 8 - 2)
  • Add: 8 + 8 = 16. (Equation: 16 - 2)
  • Subtract: 16 - 2 = 14.

Answer: 14

2. Fractions, Decimals & Percentages: The Triplets 💰

Magkakapatid lang 'tong tatlo. Pwede mo silang pagpalit-palitin. Isipin mo na lang pera para madali!

Converting:

  • Decimal to Percent: Move decimal 2 places to the RIGHT.
    0.75 -> 75%
  • Percent to Decimal: Move decimal 2 places to the LEFT.
    50% -> 0.50
  • Fraction to Decimal: Divide mo lang beshy.
    1/4 means 1 divided by 4 = 0.25

Solving Percentage Problems:

Formula: (Part / Whole) x 100 = %

Problem: Si Marites bumili ng bag. Original price ₱1,500. Naka-sale ng 20%. Magkano ang discount?

Solution:

1. Convert 20% to decimal -> 0.20

2. Multiply: 1,500 x 0.20 = 300

Answer: ₱300 ang discount. Ang babayaran na lang ay ₱1,200.

3. Ratio & Proportion: The "Recipe" Method 🥣

Pag sinabing Ratio, comparison lang 'yan ng dalawang bagay. "Sa bawat 2 lalaki, may 3 babae" -> 2:3.

Direct Proportion

Pag tumaas ang isa, tataas din ang isa. (More work, more sweldo!)

Technique: Outer x Outer = Inner x Inner (Product of Extremes = Product of Means)

Problem: Kung ang 3 kilos ng mangga ay ₱240, magkano ang 5 kilos?

Setup: 3 : 240 = 5 : X

Solution:

  • Inner: 240 x 5 = 1,200
  • Outer: 3 x X = 3X
  • Equate: 3X = 1,200
  • Divide by 3: X = 400

Answer: ₱400 beshy!

4. Motion Problems: Distance, Speed, Time 🚗

Wag kang mawawala sa byahe! Tandaan ang DST Triangle.

D
S x T
  • Distance = Speed x Time
  • Speed = Distance / Time
  • Time = Distance / Speed

5. Number Series: The "Hulaan" Portion 🔢

Akala mo hulaan lang? May logic 'yan! Hanapin ang pattern sa differences.

Arithmetic (Common Difference)

Ex: 5, 10, 15, 20, ___ (Sagot: 25)

Geometric (Common Ratio)

Ex: 3, 6, 12, 24, ___ (Sagot: 48)

Test Your Knowledge! 🧠

Ready ka na ba? Take the practice quiz for Numerical Ability to reinforce what you just learned.

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