Roman Numerals Video Lecture | Mathematics for Class 4

0:0:0: hello everyone today we are going to
0:0:2: understand A New Concept of Roman
0:0:5: numerals students do you know how we
0:0:8: write
0:0:8: for yes we write it like this but have
0:0:13: you seen what is written outside your
0:0:15: classroom above your door it is written
0:0:18: as class 4 well this is
0:0:21: interesting we can write four in this
0:0:24: way too so the numbers that we write
0:0:27: normally like 1 2 3 and 4 are called
0:0:31: Hindu Arabic
0:0:32: numbers but we also see another way of
0:0:35: writing these numbers using alphabets
0:0:37: like your class or the time on the clock
0:0:41: they are called the Roman
0:0:43: numerals we use seven alphabets to write
0:0:46: Roman
0:0:47: numbers let us see them one by one I
0:0:52: this alphabet represents one of Roman
0:0:55: numerals it is equal to one we this
0:1:0: represents five in Roman
0:1:2: numerals X this represents 10 in Roman
0:1:6: numerals L represents 50 c represents
0:1:11: 100 D represents
0:1:13: 500 M represents
0:1:16: 1,000 let us look at their values once
0:1:19: again we have I as 1 we as 5 x as 10 L
0:1:27: as 50 c as 100
0:1:31: d as
0:1:32: 500 M as
0:1:35: 1,000 an interesting fact to note in
0:1:38: Roman numbers is that it does not have
0:1:40: any symbol for zero now that we have
0:1:43: seen the values of these
0:1:45: numerals we should learn how to use them
0:1:48: to create bigger
0:1:50: numbers let us start here we have one
0:1:54: but what about this here we have two
0:1:57: ones written together so we will add
0:2:1: them we will get two in the same way we
0:2:5: have 10 XX is 10 + 10 = 20 now let's try
0:2:12: once again here we have five what about
0:2:16: now is it 10 no it is not 10 we use x to
0:2:22: represent 10 so there must be some rules
0:2:26: to write these Roman
0:2:28: numerals let us look at them one by one
0:2:32: we have three rules which help us in
0:2:34: writing Roman
0:2:35: numbers rule one rule of
0:2:38: repetition when a symbol is repeated
0:2:41: twice or Thrice its value also becomes
0:2:43: twice or Thrice
0:2:45: respectively I I is 2 XXX 10 + 10 + 10 =
0:2:51: 30 and CC is 100 + 100 equal
0:2:56: 200 however we must ensure some
0:2:58: conditions
0:3:0: the conditions are symbols i x and C can
0:3:4: be repeated three times at maximum
0:3:7: symbols v l and D cannot be
0:3:10: repeated rule two rule of addition if a
0:3:14: symbol of smaller value is written to
0:3:16: the right of a symbol of higher value we
0:3:18: add smaller value to the greater value
0:3:21: for example x i your I is smaller than x
0:3:26: hence we add them 10 + 1 is equal to 11
0:3:32: XXV means 10 + 10 + 5 is equal
0:3:36: 25 now tell me the value of
0:3:42: LV we get 50 + 5 =
0:3:46: 55 rule three rule of
0:3:49: subtraction if a symbol of smaller value
0:3:52: is to the left of higher value we
0:3:54: subtract the smaller value from the
0:3:56: higher
0:3:57: value however the symbols of V L and D
0:4:0: cannot be subtracted from any number so
0:4:3: we can have IV as four but we can't use
0:4:6: VX as 5 now can you tell how we can
0:4:9: write 9 and
0:4:11: 19 yes N9 will be written as N9 19 will
0:4:16: be written as X
0:4:18: iix hence when writing Roman numbers we
0:4:21: just have to remember these three
0:4:23: rules and we can write any number now
0:4:27: let us try to write the Roman numeral
0:4:29: forms of all numbers up to
0:4:31: 20 we have
0:4:35: 1
0:4:38: 2
0:4:40: 3
0:4:43: 4
0:4:46: 5
0:4:48: 6
0:4:51: 7
0:4:54: 8
0:4:57: 9
0:4:58: 10
0:5:3: 11
0:5:6: 12
0:5:9: 13
0:5:12: 14
0:5:14: 15
0:5:18: 16
0:5:21: 17
0:5:24: 18
0:5:27: 19 20
0:5:35: let us try to read a large Roman numeral
0:5:38: it is written as
0:5:40: XLV let us watch it closely write it
0:5:44: with some space here we know the values
0:5:47: as X is equal to 10 L is equal to 50 V
0:5:51: is equal to 5 using the rule of
0:5:54: subtraction we get XL = 50 - 10 is equal
0:5:59: to 40 now we also have V to the right of
0:6:3: it hence using the rule of
0:6:5: addition we get XEL V is equal to 40 + 5
0:6:10: =
0:6:11: 45 hence X LV represents
0:6:14: 45 very good now let us try to write the
0:6:19: Roman form of
0:6:20: 65 here we know that 50 is equal to l 10
0:6:24: is equal to X and 5 is equal to V so we
0:6:28: get 65 as 50 + 10 + 5 write their
0:6:33: symbols we get 65 equal
0:6:37: lxv so in this way you can read and
0:6:40: write all the Roman
0:6:42: numerals we hope that you have
0:6:44: understood the concept of Roman
0:6:47: numerals now here's a secret on how you
0:6:50: can study effectively with the urv app
0:6:53: you can learn with chapter notes watch
0:6:55: video lectures and solve ncer based MC Q
0:6:59: tests of this chapter on
0:7:1: urv and that's not all you also get
0:7:4: amazing courses for class 4 and much
0:7:7: more for your class 4
0:7:9: preparation thank you