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diff --git a/15_bit-manipulation/2_non_repeating_elements.cpp b/15_bit-manipulation/02_non_repeating_elements.cpp
similarity index 100%
rename from 15_bit-manipulation/2_non_repeating_elements.cpp
rename to 15_bit-manipulation/02_non_repeating_elements.cpp
diff --git a/15_bit-manipulation/3_bits_flipped.cpp b/15_bit-manipulation/03_bits_flipped.cpp
similarity index 100%
rename from 15_bit-manipulation/3_bits_flipped.cpp
rename to 15_bit-manipulation/03_bits_flipped.cpp
diff --git a/15_bit-manipulation/4_total_set_bits_from_1_to_n.cpp b/15_bit-manipulation/04_total_set_bits_from_1_to_n.cpp
similarity index 100%
rename from 15_bit-manipulation/4_total_set_bits_from_1_to_n.cpp
rename to 15_bit-manipulation/04_total_set_bits_from_1_to_n.cpp
diff --git a/15_bit-manipulation/5_no_is_power_of_2.cpp b/15_bit-manipulation/05_no_is_power_of_2.cpp
similarity index 100%
rename from 15_bit-manipulation/5_no_is_power_of_2.cpp
rename to 15_bit-manipulation/05_no_is_power_of_2.cpp
diff --git a/15_bit-manipulation/6_find_pos_of_set_bit.cpp b/15_bit-manipulation/06_find_pos_of_set_bit.cpp
similarity index 100%
rename from 15_bit-manipulation/6_find_pos_of_set_bit.cpp
rename to 15_bit-manipulation/06_find_pos_of_set_bit.cpp
diff --git a/15_bit-manipulation/7_copy_set_bit_in_range.cpp b/15_bit-manipulation/07_copy_set_bit_in_range.cpp
similarity index 100%
rename from 15_bit-manipulation/7_copy_set_bit_in_range.cpp
rename to 15_bit-manipulation/07_copy_set_bit_in_range.cpp
diff --git a/15_bit-manipulation/8_without_div_mul_mod.cpp b/15_bit-manipulation/08_without_div_mul_mod.cpp
similarity index 100%
rename from 15_bit-manipulation/8_without_div_mul_mod.cpp
rename to 15_bit-manipulation/08_without_div_mul_mod.cpp
diff --git a/15_bit-manipulation/9_square_of_no_without_mul_pow_divide.cpp b/15_bit-manipulation/09_square_of_no_without_mul_pow_divide.cpp
similarity index 100%
rename from 15_bit-manipulation/9_square_of_no_without_mul_pow_divide.cpp
rename to 15_bit-manipulation/09_square_of_no_without_mul_pow_divide.cpp