I develop in Javascript, Python, PHP, and Ruby. By far Ruby is my favorite programming language.

Together let start a journey and revisit our Ruby foundations.

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If you have any questions/comments or you are new and need help, you can comment below or send me a message.

Numbers Type in Ruby

In Ruby the two numbers primary types are Integer and Float.

# Integerage = 27# Floatprice = 79.99

Attention: In Ruby manipulating integers always end up with an integer

number = 1 / 100 # 0

Why does this division return 0? Because both numbers are integer and Ruby assumed that you would want a rounded value, so it rounded it to the nearest whole number, which is 0 in this case.

Ok but what can I get the right value with a decimal? Yes just use a float in the equation

number = 1.0 / 100 # 0.01

String to number

Sometimes you will have a string that represents numbers and would like to perform a math operation on those.

number = '1'other_number = '2'puts number + other_number # 12

This operation will return 12. String is not a number.

To make it work we have to convert string to number using the to_i method

puts number.to_i + other_number.to_i # 3

to_i convert string to an integer. You can also use to_f to convert your string to a float number.

Arithmetic Order of Operations

If we try to run this code what will be the value? In which order the operation will be run?

In Ruby the order of operation is

• Parentheses
• Exponent
• Multiplication
• Division
• Addition
• Subtraction

An old trick to remember this order is to take the first letter of each item that gives the word PEMDAS

Let's do example:

result = 100**2 + 20 - 200 / (7 - 2) + 150 + 2 * 100# 10330

Here the order of operation to make that result possible

# 1. Parentheses(7-2) = 5100**2 + 20 - 200 / 5 + 150 + 2 * 100# 2. Exponent100**2 = 1000010000 + 20 - 200 / 5 + 150 + 2 * 100# 3. Multiplication2 * 100 = 20010000 + 20 - 200 / 5 + 150 + 200# 4. Division200 / 5 = 4010000 + 20 - 40 + 150 + 200# 5. Final Addition and Subtraction10000 + 20 - 40 + 150 + 200 = 10330

Numbers methods

Here are some numbers manipulation methods

# Roundnumber.round 2.68  # 3# Round downnumber.floor 2.68  # 2# Round upnumber.ceil 2.68   # 3# Next2.next  # 3# Is number event?puts 2.even?  # true# Is number odd?puts 2.odd?   # false# Generate a random numberrandom_number = rand(1..100)

Exercise

Create a little program that:

1. Generate a random number between 1.0 and 100. That will generate a float number.

2. Use the round method to round your random number.

3. Create an arithmetic operation using all the PEMDAS items and try to figure out the result without looking at Ruby result.

Solution

number1 = rand(1.0..100).round# 74# Example onlynumber2 = 2**4 + 50 * (10 + 20) / 4# 391

Conclusion

That's it for today. The journey just started, stay tuned for the next post very soon

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